Um, the #1 warlock (of any spec) on RIO is 42nd overall in DPS.
That’s not a ‘good’ warlock per RIO. That’s the best Warlock in RIO is worse than 41 other dps. (Among all players, that same person is #71).
The second best warlock per RIO is 130th among DPS.
It’s pretty safe to say that warlocks are not in a good spot when it comes to M+.
Raiding, it’s basically afflic or bust. Part of that is more perception (any class/spec can clear at least through heroic), but groups do tend to not take and or bench people who don’t play affliction quite a bit.