There's a lot of things going against the RTS genre.

They're technically challenging to make and creatively hard to balance.

The public doesn't want to pay $60 upfront for a campaign when fun freemium games exist.

The UX does not work well on controller so a huge amount of console players will be out of reach.

Games tend to be quite long and because it's not team play matchmaking matters a lot. This push multiplayer into being highly competitive and not pushes out the casual players.

Seems like Clash Royale likes are the best we've come up with to modernize the genre but of course its very different.