Incomprehensible? How? It’s got team/channel chats, private chats, and meetings. What makes it stand out is, like everything else MS does, the integration across all their services.
It definitely needs some improvement, but “incomprehensible” it isn’t.
Channels get hidden when they’re inactive for a decent amount of time. To see them you just view all the channels in a team. Not really hard. Can also just then tick to always show it. This is a PICNIC situation.
I’m guessing your 2 instances are the personal one that is included with windows, and then the work one. You can’t have 2 instances of the same one installed.