Yuck. Not only does it break lots of things but it turns the game into utter gibberish. You can't tell who is selecting what, or what units a person should control, or how many caretakers to build or which factory should get them. If someone is reclaiming you can't even tell how much your income is coming from that.

I couldn't even tell wtf was going on in this game.

That's the exact idea. Players merge into a common entity which no longer consists of differentiable individuals. There is no more Connetable There's only the hive that matters.

You can tell what's going on in AI 10v10 where all units are controlled by a single AI instance. How's this different?