Just my two cents as a relatively new (joined 9 months ago) now 1.6k global player:
A large part of what makes our favorite game so fun and rewarding is its complexity. Sadly, this complexity is also one of the biggest hurdles for new players. I mean, even playing sim city is hard!
This complexity is I think what many people misattribute, imo, to "APM". It's not that you need a lot of clicks per second, like in starcraft, it's that you need like two correct clicks per second.
One thing that immensely helped me when starting out was to just copy the build orders and general game plan of better players so that I at least knew what to for the first 10-20 minutes, even if I didn't yet know why.
Not only was I playing semi-competent and fun games fast, it also allowed me to learn the ropes much faster compared to me just "winging it".
This was only possible though because I could choose the same map, and preferably slot, in a custom game.
In general I agree with the slow move from custom games to the matchmaker queue.
It's almost certainly the right direction for the game and its players, even low rated ones, if the "lowest common denominator" game mode becomes a chill 4v4 matchmaking queue.
The thing I'm worried about is the people who, like me, want to reduce the game's complexity via map choice.
If the only way to play ranked multiplayer were to become a 4v4 queue with 6+ maps and randomly assigned slots tomorrow, I would stick around, because by now I have actually learned the fundamentals of the game well enough to adapt.
If that would have been the only way to play 9 months ago, I am skeptical that I wouldn't have just been completely overwhelmed for 5 games and then left, never to come back.