The old-school Ataturkists who are the opposite flank of Turkish politics from Erdoğan’s party, were the very people who started this denial of Kurdish identity and territorial autonomy or independence. It isn’t just Erdoğan who has a problem with those Kurdish groups, it is Turkish society overall.

(“Kemalists” is the correct term here)

I have an incredible amount of respect and admiration for Atatürk but he also had his flaws when it came to freedom of speech, expression and religion.

What’s interesting is all of the liberal turks I know (I live in Istanbul) voted for the HDP in 2015 but are also highly critical of their association with PKK and have since switched to CHP.

Around %90 of the population in Turkey would call that group an enemy. So, it is not another "Erdogan wants to silence his enemy" case.

source?

It's not easy to find an English poll result but : https://en.wikipedia.org/wiki/2018_Turkish_general_election

Here, HDP is (in purple) PKK affiliated legal party in Turkey. You can see their support among people in Turkey. All other parties call PKK as terrorist and they are strongly against it.

I'd argue that Turkey is much more an enemy of YPG than the YPG is an enemy of Turkey.

it is a state policy not erdogan's

Tayipp is the state. Türkiye is very much a single man ruled nation.