I played single player game and just built capital ships to get a achievement. It was a Tempest Map with 26 planets.
At the end, it turned out to be a totally different game experience. 3 Hard AI were bashing me with huge fleets where I had to fortify all the planets to buy time for my groups of capital ships to move in, to defend the planet. If you are bored already, you should really try this out in Single Player or get to agree to build Capital ships only, with max 3X each for MP.



I hope there is a Capital Ship ONLY mode in MP game where you can only make 3~4 of each capital ships (or player can adjust how many each you can make, like 5X, 7X each in huge maps). (if not I am sure players will only spam carriers)