I do not know how much input Pelosi has on the DCCC. The DCCC mission is to elect people Democrats to Congress.
They however have had a big problem when it comes to interfering in primaries. I understand their position in some ways however.
One need only look at the history of the Tea Party.
The Tea Party Republicans challenged incumbent Republicans in 2010 & 2012. Often they beat the incumbents in the primaries. HOWEVER, TP-Republicans who then went on to the general election would WIN in safe Republican districts and LOSE in toss up districts.
That is why the DCCC sometimes tried to interfere in some congressional Democratic primaries. But IMO when it comes to safe Democratic districts they should keep their nose out of it!!
I had my own experience with the DCCC. In 2016, I was running for Congress in Michigan's 2nd district which was a safe Republican district by essentially 65-35. It was tough raising money. The DCCC kept calling and emailing me (as a voter) for donations. (I never gave them any money).
Finally I called them. I spoke to someone at the DCCC and he asked "are you calling to give a donation?" "No", I said, "I am calling to GET some money" and explained I was running for Congress. He forwarded me to whomever's voicemail dealt with Michigan and I never heard from them again .
but their interference on the part of incumbents in safe Dem districts is despicable- I don't blame AOC one bit for not playing ball with them