Erdogan attacked Kurds long before he lost his parliamentary majority. He attacks them because it's politically convenient for him to have a unifying enemy (most non-AKP Turks do believe the Kurds should renounce violence and drop their separatist demands). In fact, the HDP reached such a high level of support in those elections because a lot of people finally saw through the game and were tired of playing it.

I don't disagree that Erdogan all but helped IS/Daesh against Assad and Kurds, I'm just saying that his attitude towards the Kurdish problem has been more or less the same since the '90s.