If this investment tool remains symmetrical and available for everyone, it would mean that the wide would also have access to this tool. Since the wide would get the required resources faster just by harvesting the empty systems, it would invest faster and get rewards faster. That's how yet another snowball would start.
It would need to be based on a resource like influence that doesn't scale with empire size. It has to be "Do I spend 150 influence to add another habitat, claim 2-3 systems, or add 2 more base growth to my capital?" You can spend that influence on one of those three options and you might be able to split it up like claiming 1 system and adding only 1 base growth to your capital. However, it has to be a system where you can't just get bigger and then choose all of them, and if you want to do all 3, you have to do one, wait for influence to accumulate, do the next, wait, and then get the third.
It's why their stance of never offering infinitely scaling increases to influence is a good one, and I'm glad that they're removing some of the uses so that it can be focused into the core areas of growth in the game. Keeping the influence progression to one or two techs, a few traditions, and two very powerful options in the form of a unity ambition and the custodian all works pretty well for this.
While the new tool may make both the tall and the wide equally overpopulated, the tall would very fast hit the limit on districts and buildings and there would not be enough jobs to maintain parity.
Scaling up district counts with fewer limits and/or adding jobs even after you've already built all districts and buildings would be another important component, yes. I think that's less of an issue than pop growth is at the moment, though. Since the pop growth cost change, your empire doesn't fill up at such a snowbally rate. The way it's set up is actually really clever. If you are consistently increasing your pop growth as you increase the number of pops in your empire, the pop growth curve ends up being fairly linear (or at least more so than before). It only starts going exponential or logarithmic if you're expanding your growth speed increases faster than the cost increases or if you're not keeping up with expanding your pop growth.
I also think it's fine to have limits on certain avenues of growth. Peaceful expansion hits a wall once you've claimed all accessible systems. Now you have to either build megastructures or go to war to continue going wide. Aggressive expansion might get stymied if you're blocked in by fallen empires, marauders, and/or advanced start AI, and you might need to turtle up a bit and advance enough that you can make a more aggressive move.
Diplomacy is another avenue for increasing your strength by effectively putting more pops behind your empire's strength by partially adding the strength of your federation mates, which is why I think various diplomatic maneuvers cost influence. It could still use some improvements, but the foundation is there, especially since the AI has been getting incrementally better the last few patches.
Still, the same thing applies. The new Sprawl is just rubber banding so Tall can try (and still fail) to keep up. Because it sure as heck won't stop Tech Rushing, because you can just replace all those jobs that use to be Sprawl jobs with Tech jobs, and you'll burn through the Tree even faster than before.
I don't think the purpose of the rubber banding introduced by sprawl is aimed at the tall vs wide. It's honestly nothing more than a side bonus. If you reduce the distance between empires are ahead and empires who are behind, it "helps" tall due to the fact that it's a weaker strategy. If the main goal was to introduce growth options more consistent with a tall style so it can be properly competitive, then yeah, I think they missed the mark. Planetary Ascension is one possible method, but with it coming from a resource that you can scale up as you grow, it's not an alternative to wide expansion; it's something you can simply do on top of it.
What sprawl's rubber banding does achieve is making games closer and thus, more interesting. It also smooths out the tech curve a bit by adding a cost increase throughout the game that's dynamic to your empire size to go with the cost increase you have as you get into later game techs. I think the tech costs don't increase enough in the beta to achieve this (in my current play through, I have 3 completed ring worlds and took down a fallen empire before 2400), but the core approach works. If you double your size and double your research output, you no longer halve your research times. They're better, but not twice as good, and that's the main purpose here. I think the system is good, but the numbers need tweaking.
The recent pop growth changes introduced a similar rubber banding effect for the number of pops. If you double your number of planets and therefore double the amount of pop growth you have in your empire, the actual rate at which you get pops no longer doubles because more pops means you need more growth.
I think Wiz is right that rubber banding mechanics can feel bad, but I think the solution there is to make them more subtle so they don't feel like they have a huge impact, and to make them bonuses to people behind instead of penalties for being ahead. It's the difference between Mario Kart's blue shell and their subtle adjustments to kart speed based on how far ahead/behind you are. I by no means want a metaphorical Mario Kart blue shell in Stellaris. That would not be fun. The subtle modifiers on speed to encourage closer races, though? That's an approach that translates well to Stellaris, and I like how they've been making advancements there recently, with this sprawl shift being the right direction.
Honestly, I'm coming away from a lot of these discussions suspecting and hoping that these recent changes are setting the stage for a more thorough change to expansion. With some rubber banding for pop count and tech/unity advancement plus unity made useful while removing some of the old non-expansion influence sinks, I think we're set up extremely well for the introduction of new ways to grow internally using influence to provide taller options for expansion than we currently have. Situations might be their way of making those options more interesting than just clicking the upgrade button on your planet every few years as you gain influence, and that might be why we haven't seen much in this direction. I suppose we'll see.
