If you resupplied a fleet the ships would loose supply while others where getting resupplied - thanks to the moving planets in sectors. If that weren't bad enough, resupply is 1 at a time .. good luck doing it with a fleet of 300 ships
The game really fails on the large scale though - subjugating empires is pointless, they rebel within an hour. So you gotta play whack-a-mole in space-empires scale. Then there is the problem that unless you take automation of mining bases from the AI your empire will be in the reds very fast. Civilian ones don't cost you anything, but your own built do, and a lot. (Also, the game never says it - but mining bases always also "mine" luxury resources if you put a mining device on them)
Generally, i absolutely disagree that this is a good 4X game - here is what you don't do in this game
Explore = The AI explores automated, your only explore part is clicking on yes/no (usually) If you don't let the ai expore, you still just say "explore this sector" because of 700000 planets everywhere.
Expand = Your only action in this matter is pointing at a planet, then its automatic all the way from colony ship to super mega homeworld planet. Building manually is pointless - you need a lot of ships for civilian protection. Forming fleets is your only "expansion" but then we go back to play whack-a-mole. No colony management beyond taxes - and often you don't have much choice in taxes.
The weapon ranges in this game mean that defense bases are useless. There are no minefields, no drones, automated defenses, no local police forces/militia or anything like that.
Exploit ie. Research its random lottery based, you can't even give general directions - game researches for you. Mining is automated, trade is automated. Everything interesting is automated too.
Exterminate = its downright impossible to exterminate anything in large scale. You can conquer, but even then thats a bad choice.
This game is more a civilian trading sim with tacked on military. and lets not get me started on how large combat works on this game. AI War does combat infinitely better/smoother than this without even being 4X game.
My main problem with this game is this.
Every single round plays out exactly the same, same research progressions, same ship upgrades, heck apart from engines there isn't even such a difference between the races. Like you, i got bored 15 hours in, i had 150 planets on a 600 planet map - 400000 in money per tick. Thousands of ships and 2 fleets with 100 deadnoughts each. Even if you play merchant the inevitable combat means you will either go red, or play an eternal game of catch the rebellion.
If had to chose between MOO3 and Distant Worlds, I'd play MOO3
Also - The graphics are absolutely completely butt-ugly. And the game runs, *really* bad in late-stages.
Also, if you wondered why my opinion sways from awesome 4x to broken by design, the reason is was playing yesterday a lot of this game - and at some point you realize, what you are doing is not playing a game, but watching an interactive screensaver. It made me go back to 4x games like MOO3 to see why i thought this and i realized, if you let moo3 sit around for 30 minutes having a script press end-turn for that long, once overy 30 second, you have lost.
If you do it in Distant Worlds, you can let the game run over breakfast, and come back to a game that played itself without you.