another point of frustration is faction unrest, planet unrest and the global/local economy.
so I'm doing a pacifist materialist run, to play tall and try to survive trough allies and federations, and of course when you do that stellaris spawn next to you a fanatical purifier.
war ensued, and I managed to catch a couple planets and work around their superior fleet power enough to reach a status quo agreement. now these two planets were at 5% or something stability. that immediately tanked my empire economy, because of course you get almost nothing out of them but you have to pay maintenance in full. and this caused an interesting conundrum: with the economy shot I could not build strongholds, with their planets being goods black holes I could no longer sustain happiness on my own colonies, so their economy tanked too, and it all went to shit until one of the planet finally rebelled: I gifted the rebels all the troubling planets and then went on a liberation war to change their ethic to pacifist, ending the purifier problem at the door for all.
at that point the economy kinda recovered and I managed to build some commercial zones and stronghold here and there, regained some stability, but because that takes time and the war angered my most prominent faction another rebellion ensued bearking the empire in half. and of course, while playing as a lost colony, my parent empire granted the rebel independence.
I understand having to deal with problems on captured planets, and rebels and factions and whatnot, but if defending completely ruins the economy in a downward spiral I'm left with no way to deal with it, short of creative wars (yay pacifist right?)
there's a lot of wrongs in this societal/economical model. pacification measure all drain on influence, which hits hard pacifists as influence gets drained already by faction management AND trade deals. a rebellious planet pop and building upkeep draining resources from stable planets, ruining their stability, is major bullshit. also, a recovering planet should not be rebelling that easily. and that you can't use armies to pacify planets, only strongholds defensive armies, is some other bullshit, as with the economy shot you can't build strongholds but you still have them armies, sitting there, watching rebel with a beer in one hand and their dicks in the other.