I never really got into SC2, but Warcraft 3 and AOE2 have pretty major problems with online gameplay due to using deterministic lockstep. Back in the day, it wasn't uncommon for people to lag out in Warcraft 3, which would freeze the game for the whole lobby until either enough time passed that you could kick them, or they stopped whatever was making them lag in the background.
My friends and I actually quit playing AOE2DE because about 1/3-1/2 of team games had someone lagging from the start, which makes the game slow and choppy for every other player (and this was despite the game having a benchmark you had to complete at a certain framerate to play matchmaking online). Spending the next hour in an unplayably laggy mess of a game just isn't fun.
I know Supreme Commander (supcom) also has problems with 1 player lagging causing everyone else to lag.
There's also the matter of it being much harder to actually program a deterministic game, especially once you try and multithread it (which is really necessary for modern RTS, but a nightmare for determinism). Fixing all desyncs is very difficult (AOE2 and WC3 both still have desync bugs. In AOE2DE some people use them to cheat their way up the ranked ladder, desyncing whenever they're losing so it counts as a draw instead of a loss). I've heard the upcoming Sanctuary RTS (indie supcom spiritual successor in development) talked to a bunch of RTS industry vets, and were told that it's not worth it to do a deterministic simulation these days unless you want over ~10k units. AI War 2 [1] has a pretty interesting network model for multiplayer, where they've got a semi-deterministic simulation, and self heal client's simulations if they diverge from the host, which allows for it to be heavily multithreaded and have 10k-100k+ units. You'd probably have to use dedicated servers for a competitive ranked mode if you went that way (and they'd be heavier to host, for a smaller per-game player count than eg. an fps or a survival game).
My friends and I actually quit playing AOE2DE because about 1/3-1/2 of team games had someone lagging from the start, which makes the game slow and choppy for every other player (and this was despite the game having a benchmark you had to complete at a certain framerate to play matchmaking online). Spending the next hour in an unplayably laggy mess of a game just isn't fun.
I know Supreme Commander (supcom) also has problems with 1 player lagging causing everyone else to lag.
There's also the matter of it being much harder to actually program a deterministic game, especially once you try and multithread it (which is really necessary for modern RTS, but a nightmare for determinism). Fixing all desyncs is very difficult (AOE2 and WC3 both still have desync bugs. In AOE2DE some people use them to cheat their way up the ranked ladder, desyncing whenever they're losing so it counts as a draw instead of a loss). I've heard the upcoming Sanctuary RTS (indie supcom spiritual successor in development) talked to a bunch of RTS industry vets, and were told that it's not worth it to do a deterministic simulation these days unless you want over ~10k units. AI War 2 [1] has a pretty interesting network model for multiplayer, where they've got a semi-deterministic simulation, and self heal client's simulations if they diverge from the host, which allows for it to be heavily multithreaded and have 10k-100k+ units. You'd probably have to use dedicated servers for a competitive ranked mode if you went that way (and they'd be heavier to host, for a smaller per-game player count than eg. an fps or a survival game).
[1] https://wiki.arcengames.com/index.php?title=Category:AI_War_...