I don't really see the big advantage of that combination.
A Catalytic Drone requires 9 Food at base instead of 6 Minerals, so half the benefit of it being a more efficient resource to produce is already gone. From that point on, it also scales badly, since +Yield Building for farmers still only get +1/+2 to a base value of 6 (+33%) vs. +1/+2 to a base value of 4 (+50%) for miners.
On the positive side, tree of life guarantees farming districts, but then again, districts are usually not an issue. And you can specialize heavier into +food bonuses, but those don't really do that much in the grand scale.
So, how is that worth a Civic Point? It seems to just... change things, without really giving any obvious benefits (besides the machine-empire exploits). Which is cool for roleplaying, but in terms of stats? What am I missing?
Your decades before you get the farming and mineral boost buildings.
Catalytic Converters is an early-game economy buff by letting you shift your economic burdens and resource chokepoints away from minerals and onto starbases, letting you maximize pop-efficiency at the point in the game where you have the fewest pops to spare and making use of early conquests the most. It's very much a 'early advantage to get a dominant position' economy- yes, if you had two economies in isolation the mineral-alloy would eventually achieve higher efficiencies, but in practice the game is more likely to be decided by the party with
earlier population economy efficiencies.
As a hivemind, in your first 30 years your largest economic base can/should be your energy and food production, not from pops but from starbases. Gestalt get not only the hydroponics bay, but also the solar panels, which for a total base cost of 350 alloys have the output of about 3 worker pops. 12 energy/10 food, pre-tech modifiers. With your first 4 starbases, this can be 48 energy/40 food, which would take about 12 pops on your homeworld to replicate at a time when you don't even have 40 pops.
Stack on the Unyielding tradition as a first tradition, and bee-line to the +4 starbases and 50% starbase upgrade cost, and you can upgrade 8 starbases for the normal cost of 4, and if you foot the bill for the buildings (which don't get discounts) with 8 built starbases and your starting capital starbase you're looking at about 100 energy and 90 food in the first two decades of the game just from starbases. (2000 alloys for about 24 pops of output at a time when most empires don't even have 50 pops.)
That 90 food can cover about 10 capital-world alloy workers- or 5 alloy districts- for over 30 alloys a month when you factor in stability bonuses. That alone will pay off all the starbases in about a decade, and power fleet creation thereon, and this is just the self-covering investment. You can use your drones as miners/farmers to cover more production, especially if you take the phototropic perk for halving food upkeep (leaving far more food for alloys for the same number of 'normal' farmers).
That's a
lot more alloy production than could be feasibly supported through mineral-based alloys without eating into your science budget as heavily. If alloy workers and scientists both take 12 minerals upkeep, you're not only slowing down the rate of expansion you can build buildings at (because each science lab/industrial district lowers mineral income by 12), but have fewer pops available to work as scientists/alloy workers because you need pops paying the mineral upkeep, rather than starbases paying the food upkeep of the alloy foundries. You're not only buying
more buildings more easily, but sooner, getting the benefits of early-game shifting months or even years ahead of what -12 mineral income delays would cause. And with starbase food offsetting your early job upkeep needs, you have more pops free to
be more productive specialists rather than resource-upkeep.
Minerals could technically be covered if you used Nebula Refineries, but nebula are extremely unreliable RNG. Catalytic converters is both early and extremely consistent,
and frees up your engineering tech priority tree. By shifting the alloy-upkeep economy to the Society Tree (otherwise with little early game military relevance), the player is freed from the need to boost mineral economy techs and can focus on other early techs instead to win wars rather than support alloy economy. This, in turn, means an easier time prioritizing +100 hulll point corvettes, armor, and what not instead of spending years on the mineral-economy tech to afford more alloy and science production.
Put it together, and you can get an extremely strong tech-and-food-alloy economy up and running not only before a mineral-alloy economy could afford to build the buildings, but a larger specialist economy as well because you need fewer starting-pops devoted to mineral upkeep. By the time mineral-boosting buildings come into play, you should already be able to conquer another empire, take their homeworld, and be snowballing as you can then afford even greater science and alloy output.
It helps that catalytic converter hiveminds can turn early-game conquests into alloys in a way that mineral-hiveminds can't. If you are a normal hivemind, livestock covers food upkeep for drones and that's it, with food being nothing but a resource to be sold at bad exchange rates. You still need the same number of miner-drones for the same amount of alloy job upkeep. For Catalytic Converter hiveminds, livestock are alloy upkeep that you don't need to use your own drones for, freeing them up to work as specialist jobs (including more alloy workers to conquer more livestock).
