Even in SC2, click-speed is not a significant determinant of winning or losing for anyone below Diamond. It's simply not an issue for the vast majority of the player base (75% of players are Platinum league or below) so I don't know why so many people have fixated on that as the thing to blame problems on. It's like saying "basketball revolves around dunking" even though dunks are basically not an element of the game for anyone playing below the professional level.

Insofar as there are barriers to entry to the game at lower leagues, the challenge is more the mental challenge of keeping track of a bunch of different variables and keeping up with the multi-tasking. It's not nearly as execution dependent, at that level, as most fighting games or even a Soulsborne. It's a mental acuity and habit-formation challenge rather than a dexterity one. Better players will have more actions per minute (assuming they're not spamming), but it will be because they're making decisions more quickly, not because they have concert pianist fingers. I got up to Gold league playing mostly with a trackpad. I know someone who got to Diamond on a trackpad as well.

There's lots of problems with SC2's design, but they mostly center around a poor onboarding experience, doing a bad job of communicating the ripple effects of early decisions, a surfeit of high-lethality units that settle battles or games in a second, and the availability of multiple "cheese" strategies for each faction that are much much easier to execute than they are to defend against. But those are all addressable within the broader framework of a Blizzard-style RTS with better unit design, UI/UX, and tutorial or single player game modes.