@bunkerman I will defer to your extensive experience in the area then, I mostly base it on my lifeseeded no robot games which felt like a reasonable starting point for a comparison.
I play without ascension paths here and there, sometimes just because I feel my race should not be able to ascend for whatever reason, and sometimes because I just don't generate enough unity because it goes against my idea of the empire. The first part does come fairly early, yes, but at that point ID has already accomplished so much because early economic advantages are just that big. That is unless you're playing on really low tech costs, then it clearly hasn't had time to do much yet but it's such a special case and I'm not even convinced it works against ID because lower tech costs means higher income faster, which makes influence being the expansion limiter more pronounced.
I did mention genociders as a possible exception to picking ID, but ID is still solid even for them just because it allows you to activate more edicts. That's even though the benefits of the perk falls off to 0% when you can no longer expand without war, just because early benefits matter that much. It's certainly weaker at that point, but it's still not terrible. Playing a genocidal empire also has other drawbacks that works against your expansion plans, depending on how much of a threat AI empires are to you with your settings. You also can't ignore the benefits of other government types as they relate to expansion. Any regular empire can be a xenophobe, which makes outposts cheaper. Fanatic Egalitarian is very good for expansion too, simply because it provides you with a very easy to please faction early, and improved influence from that faction, for an easy +3 influence which is a pretty insane boost early in the game. Mechanists for early robots to more quickly move into droids which allows you to more efficiently colonise more planets sooner. Rapid expansion is the game, but there are many ways to play it.
I don't think any of those three things are real to the extent that it makes much of a difference. Slower traditions, because you still have to pick a tier 0 perk, and it will still be the best one unless it's so slow that you can get Voidborne without holding the perk for a significant amount of time. A more crowded galaxy just shifts the use more towards the claim cost reduction rather than the outpost cost reduction. Being boxed in, because being boxed in by something you either can't bypass or kill fairly early is quite rare. I almost never encounter it even though I regularly play on below default hyperlane density. I also know a lot of people who just restart the game if they get boxed in really badly. A lot of the aliens you can just move around, even some of the leviathans, and build on the other side. If it's an AI empire you can also go through their territory and build somewhere else unless they closed their borders off, which is something you can affect against most empire types. Is it possible to construct a scenario where ID performs poorly? Absolutely. The same can be done for ascension perks. In this scenario your neighbours are all spiritualists, and you turning your pops into cyborgs gave them the additional opinion malus required for them all to declare war on you.
There's also the part where the ascension paths are actually two perks, not just one. We were instructed to evaluate their strength based on it taking up two perks and as such have to cut the total benefit into two.
Well, again, "sub-optimal" depends on what we're optimizing for. If it's beating a 5x crisis or an early crisis, then, yeah, ID probably has to be in the mix. Usually it'll depend on galaxy settings.
To an extent, yes. If we use what is in the original post and also what the thread creator said a few pages back that the goal is to win the game, and beat the crisis, and do so on a setting that provides the player some challenge, I think you want ID an overwhelming amount of the time. Personally I wouldn't mind it if the remaining three ended up as a tie just because of the mutually exclusive nature of the two ascension paths, and unless you're doing something quirky you'll want ID + one of the two nearly 100% of the time. Something has to win though
(Also, I'm a big fan of your signature)