I think you don't like the calls to "nerf" units , but that doesn't mean making the game more boring, to the contrary : what MPs players don't really like are too anchored 'metas' that make all games a bit too similar... Because one build or tactic is too hard to counter, and that therefor a players can repeat it regardless of the opponent being aware of what you he'll do.
Ideally strategy, improvisation, adaptation would be rewarded over mechanically applying a cookie cutter build. You get a better experience from a game where you have to use your brain, teamwork, rather then just trying to be fast fast at spamming broken champ cav for example.
Idk how exactly that translates for SP, probably just not being incentivize to make an army of 1 unit type, because it's stronger and isn't at risk to be countered, is already kinda giving the game an extra dept. Pretty sure that it's universal that players play RTS for the Strategy part (Even if I've been told that "Real Time" means it should be about being fast clicker or what not).