You can believe whatever you want, but Blizzard did purposely hose the Warlock class in favor of Demon Hunters. They destroyed Demonology so that they could make some money off of the Demon Hunter class! There was nothing wrong with Demo spec for multiple expansions, and their argument about a return to "summoning" was complete BS! The demo spec summoned demons just fine even with metamorphosis and Dark Apotheosis in the spec throughout MoP. Blizzard themselves altered the spec in WoD to summon less demons, and then NERFED the spec into the ground in 6.2 to get people to stop playing it.
That's not a conspiracy theory, those are the facts! You can read about it yourself since it only happened a few years ago.