1. You have proven nothing other than that you don't have any valid points "against" locks.
2. Your last statement "proves" how less you know about that what you are talking about ("mythic progression", nice try, lol)
To become more serious: I've had tons of situations where the fact that i'm a warlock helped my group out more than any mage ever could. For example tanking Odyn for 15 seconds due to a tank death so that we managed to kill him in time, instead of not beating the timer. Doing the last 20% of a mythic dungeon boss solo 'cause "i could" and the rest of my group died, soaking things during raid encounters where EVERY other DPS dies, enslaving demons to abuse their overtuned abilities and all that stuff.
DPS is not everything. In vanilla times paladins have been brought to the raids JUST FOR THEIR BUFFS. Today everything is that simplyfied that these concepts won't work anymore. But seriously, how can the option to talent into 2 AoE stuns, 2 Interrupts, Dispel, Seduction, AoE Fear, Instant 3sec Horror, 2 Range Stun and all that stuff be a bad thing? It isn't.
And here is the keyword what warlocks bring to a group: Versatility. The lock can adjust to any type of group no matter what is needed. In the current easy-mode game, at least for me, that is more worth than a baseline interrupt or 10k DPS due to taking Sac on trash pulls. That our DPS sucks without talent X is just plain wrong, it is lower, yes, but not completly gimped to a level that make us "useless".
Good groups know about these facts. Bad groups, and bad players, reroll to mage.
The only sad thing about those people is that they go out in the world and scream that warlocks are bad, and that those people will actively prevent warlocks from getting back into mythic+, even when they themselve play so bad that they get easily beaten by any lock out there.