As a way-left progressive who constantly tries to pull out his nonexistent hair over how bad progressives are at messaging:

It makes me laugh that progressives complained about how well Pete was doing when all he had was a likable personality, good speaking voice, and a personal narrative--all while gesticulating wildly at everyone else's unread policy memos--as if those likeable traits aren't exactly what laypeople voters care about as demonstrated by every election and poll ever.

This isn't a congressional committee, it's a presidential election; people are looking for a leader, not a policy wonk.

It's possible to be progressive and likable at the same time, you just need to blend the right personality and rhetoric.