The history of Turkish forces prosecuting Kurdish civilians makes the whole matter extremely murky. Even the PKK does have quite legitimate and understandable goals and motivations, though it has been criticized for its methods which could be called "terrorism". But the same can be said of the Turkish state.

As a total outsider I see the situation as somewhat related to the Palestinian struggle: The more you are struggling for basic survival in the face of aggression, oppression and poverty, the less energy and motivation there is to curb the excesses of extremists in the own ranks.

I'm very sympathetic to the YPG, and I don't think they are a subsidiary... but any objective observer can see that YPG and PKK are very closely related. They have posters of Abdullah Ocalan everywhere, they have many PKK fighters in their ranks, etc. etc.