Basically, time investment makes me unwilling to jump back in. The time it takes to make a single player replay is unavoidable, but multiplayer is basically pure tedium for me. If you don't winstreak, you spend more time waiting in queues than actually playing. And you'll frequently have to either deal with a godking 4D chess master currently on their 235th win in a row, or a person using a copy pasta'd min-maxed move every round and has virtually zero counterplay other than use the exact same move, when you do finally get back up. Of course, it depends on the game mode, but every game mode has it's meta move and it's derivatives.
If multiplayer could have multiple matches occurring in the same lobby, basically lobbies functioning as chat hubs, and you were free to join "rooms" within the lobby to either play a match or spectate one that's going on in that room, that might alleviate some of the tedium. Each room can still have a king of the hill, so to speak, which allows the winners to still maintain win streaks, but losers don't necessarily have to spend time waiting in line if a room is available that can support other players.
Like, for example, say 7 people are in a lobby. 2 of them are just spectating because they want to chill, 1 is spectating but in queue, and the remaining 4 are playing out matches in rooms. Room A finishes their match with player 3 winning. The loser, player 5, is pushed into queue and the spectating player in queue joins the room to play the winner. Shortly after, the match in room B ends, so player 5 joins that room to play the winner. While these two matches are going on, another player joins the lobby, and that player along with the one in queue open up another room within the lobby. The players who are spectating are free to jump between the rooms to spectate whats going on, and all chats are linked.
That setup would be more enjoyable for me, since it reduces down time when you lose, without having to server jump.