It still competes with SO because now you'd post the question about a certain framework or library on its repo's discussions. Also, isn't it kind of explicitly doing that because discussions can elect an "accepted" answer?
Accepting an answer is an attempt, but without the moderation, editing, voting, duplicate closing and so on from SO, the quality and ease of finding answers won't be there.
I'm sure plenty of people remember trying to find answers through forums, and it was a nightmare. The thread might not actually have an answer in it, and even if you get pointed to an answer, it'll often need context from the rest of the thread, it might be out of date, or completely wrong.
To put it simply: there is a reason why people use SO almost exclusively for Q&A, and there is a reason people still use forums and stuff as well. Discussion and Q&A have different goals and conflating or combining them leads to pain for users.