PVP sucks in RTS games because it's basically a solved genre

>economy management
>rush vs boom economies
>unit counters
>micro
>manual abilities/ground fire mechanics
>hotkeys and unit grouping

if you can learn learn the basics and metagame of 1 RTS you're on your way to being able to learn 99% of them. This means that grognards who have been playing these games for 30 years are going to have a MASSIVE advantage over a casual who, every time they engage with PVP, gets overwhelmed by someone who maybe has decent competency in like 2 core mechanics. It's unfun and getting good in that type of environment is punishing as all fuck.

There's a reason mobas killed any interest in RTS for a long time and it's because you could much more easily be matched with people in your skill level and the mechanics you had to manage up until you started gettiing to higher brackets were extremely basic. RTS games are harder and people don't like to be slapped around. It's honestly a similar problem to fighting games. Please note that I'm not saying we need to dumb everything down for casuals at all, just that you shouldn't expect the genre to grow nearly as much as much more accessible genres.