Not the GP but I’ll give my take:

The long term value for an RTS is with the multiplayer. The problem is that the games are incredibly demanding to play. It takes a lot of practice and experience to get good enough to get off the “bottom rung” of the online ladder, just to be able to reach close to a 50% win rate.

Many gamers find this too stressful to deal with. They end up quitting the game and moving on to something else. This causes the “bottom rung” to move up in skill, as the weakest players leave. Since winning in these games is zero-sum it gets harder and harder to win the more weak players leave. Eventually only the most dedicated players remain, making it extremely difficult for new players to break onto the scene.

The other aspect to RTS games, the single player campaign, takes a lot of effort for the developers and designers to build. Unfortunately it has very little staying power. People play through the story maybe once with each faction and then either try out multiplayer or move on to a different game.

I think that's fairly accurate, thanks for putting it into words!

Hit the nail on the head. The execution requirements for RTS games are steep and the competition is fierce. You have to completely re-arrange your priorities from "win games" to "be better than I was last match, and I'll get there eventually", and it's something that modern audiences don't see often and struggle to engage with.

I think the other thing that is that the RTS community has de-emphasized modes other than 1v1 to the extent that it's basically a 1v1 game like fighting games. At least with MOBAs there's a destressing factor of losing with a team that stops the feeling of sole total responsibility that makes so much ladder anxiety. Similarly, arena shooters also have team deathmatch modes.

I'd say it's like this for any older game which still has a multiplayer community regardless of genre. There just isn't a big influx of new players and the bad ones give up.

That may be the case but other genres, such as shooters (first and third person) have found ways to get around it. Fortnite, for example, has nowhere near this issue whereas Quake 3 is plagued by it. The 100-player battle royale structure of Fortnite is one mechanism I think helps to mitigate the problem of overwhelming skill gap.

This kind of thing hasn't really been tested in RTS games, which usually focus on 1v1s.

Fortnite's solution has been bots, which is not very popular because plenty of people think they're above bots. Or think that bots cheat (which is true in Starcraft). Or in fighting games, they don't play like humans so you end up learning bad habits.

They didn't cheat on sc2 did they? They did in sc1. But regardless, with the breakthroughs in AI recently, I don't think they'd need to cheat on a hypothetical sc3.

I know in SC2 the harder AI would get free resources.

I think "playing like a human" can still be an issue depending on the game. Until people want to play against AIs, there's not a lot of work put into making AIs human-like rather than just AI players.

Also there still Starcraft 1 AI tournaments which are interesting. https://youtu.be/gqggsFpTAt8

Probably doesn't need to be perfectly human-like. If you want human-like, play against humans :-) Just keep it as fair as possible with the AIs.

I didn't know they were still doing SC1 AIs, I always wanted to make one but never quite figured out how to get started.

The big issue with bots is that they are almost never good enough to beat a moderately skilled and muscle-memoried human player. People who try to use them to learn don't end up being any better than a n00b, as it were.

Randomness is a big mitigator.

In MtG or LoL, a worse player than the opponent might still win 40% of games (luck of the draw or teammates), even ignoring matchmaking systems.

Players can aim for losing less over time, while still having a chance to win any particular game.

In SC or chess any chance of success against a better player is effectively zero.

I taught a friend to play multiplayer Supreme Commander. And your outlining of the "on boarding" problem is spot on. They ended up getting through it because they already where a good RTS player and I 1v1ed them for a while (didn't abliterate them every match, and slowly ramped up the difficulty while providing constructism). However most new players don't have access to 1 on 1 coaching!

RTS games are just too stressful. They require 10+ minutes of full concentration. Whether you've just won or lost an engagement, you better keep up with scouting, building your army, gathering resources, expanding your base, preparing for the next engagement, etc. You get absolutely no downtime.

Every other game gives you downtime. Shorter round based games like fighting games give you time to catch your breath. Respawn time is a reprieve for both sides. Even just being on the queue screen for Starcraft II was enough to get my heartrate up in anticipation for the stressful games.