I mean, you're not wrong on multiple accounts here, although you'd handily lose a bet on finding exceptions to it and I'd feel bad pocketing the price of the Storms DLC with such an easy layup (Cosmogenesis doesn't rely on Fleet Power to work and get away with avoiding the latter parts of the game entirely).
However, my question to you is kinda philosophical - Have you ever tried to get as far as you could by purposefully neglecting that facet of the game and how does that work? Often enough, some of these summary gripes about what works seem to be 'I solved the game and there's nothing to do now until the game forces me to resolve it with changes'. I can't account for why 'How would I do X if I couldn't do Y along the way' is a fascinating question for myself and not for you, but a small hunch of mine is that players themselves are supposed to figure some of this out for themselves once they've reached a comfort level with the game and not wait around for the devs to throw a new rake in your path or make the current rakes better rakes.
Some of this is all for nothing if the game system mechanics also don't please, or the overall game system is overwhelming without meaning or importance, or the UI introduces a new cooldown counter you can only see in one place in the UI completely unrelated to the decision to start cooldown, but...
It is kinda baffling to socially hang around a game for 8 years that likely isn't gonna get shored up in particular detail to make fleet power less of a path of least resistance in all the ways it is, and not even be interested in the extreme contra nullifier to the thesis and making it work, out of spite almost. But that's the diagnostician POV and its really hard to impart that upon others.
Cosmogenesis buffs fleet power again by unlocking more or better ways to increase it, and ultimately it heavily relies on fleet power to be successful. You can try to shoehorn your way to victory by playing diplomatically, but that’s just borrowing fleet power from other AIs to protect you. Again, it's all centered around the pivot point of limitless scaling fleet power.
I often purposely tried to avoid a certain playstyle just to see how far I could get with one arm tied behind my back, only to find myself scaling my endless doomstack of fleet power, coming from another source. This is what I meant when I wrote that the curtain was drawn back, the smoke vanished, and the mirrors shattered.
Overall, I really like the concept and the flavor the game provides, and how much fun it is to play multiplayer with friends. The empire management and the amount of it is really neat and engaging, but it all comes crumbling down when warfare starts. The fleet power arms race takes over the game and sucks the fun out of it. That’s why I stuck around so long—because I like the concept and many aspects of it, but the fundamentals are just rotten from my point of view.
In some way or another, you may feel that your fleet power is all that matter, in one way or another, you always need to have a bigger fleet power of everybody else or be vassal of someone with more fleet power, or a federation with more fleet power. But if you think about it, you will notice that what realy only matter is the number of pops you have, as the number of pops translate directly in economic power, and with it you can build the fleet, that is needed to have more pops, either by conquest or giving you time to grow/build more pops. Then you notice that the only thing that realy matter is tech, because it increase the efficency of your pops and your alloys spending and naval capacity in fleet power, so everything you do you need tech.
It's not a problem of "with this I do everything", it's that you need to do everything. You need pops, you need tech, you need fleet power. Whatever you do, you will feed on all of them or feel useless. Only with the last few updates we had some different gameplay loop that moved away slightly from the number of pops hegemony.
I don't feel the system is "simple", I feel it's forced. You need to have everything, tech, unity, pops, fleet power (some way or another /by group ) otherwise you lose it all.
I understand your perspective, but tech is not the only way to endlessly scale your fleet power. You can even scale it by not having many pops. You can play diplomatically and just "borrow" fleet power from vassals and scale that way. The only really important thing is, if you want to be successful at the game, stay alive, or have something to do, you need some sort of way to scale your fleet power—that’s what matters. Whether you reach it by just making more alloys with pops, making more tech with pops, or making friends through diplomacy, or any other conceivable hoops and paths you take, you will ultimately just scale your fleet power.
The real deception lies in the idea that you are making meaningful decisions and playing different playstyles when the ultimate question to it all comes down to, "Ok, how do I scale my fleet power with this if push comes to shove?"
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All these are just side notes on why I’m personally not really excited about the DLC direction and the upcoming Storms DLC.
It somewhat aggravates me that they know their fleet power scaling is damaging the game, and now we have moving storms that will increase the rock-paper-scissors effect, making brute-forcing your way to victory with just more fleet power not as easy anymore in some RNG cases. For example, when you land your fleet in a system where a -100% armor storm is raging, and you lose the rock-paper-scissors battle against a fully shielded fleet half the size of yours. At least, that’s what I expect to happen based on the dev diaries I’ve read.
They know their military mechanics are bare bones and oversimplified, don’t fit the pace of the game anymore, and hold back real asymmetrical playstyles and mechanics. But instead, they’d rather build in gimmicks that sometimes, somehow, maybe reverse or change the fundamentals for a moment, but not the necessary changes that are really needed to "fix" it.