This seems very common in JS land, I once saw a talk in a conf which seemed very basic, later on I stumbled onto a tweet about how the speaker often submits abstracts to CFPs often not knowing much(or at all) about the subject, which serves as motivation to learn and talk about it, works well after having a track record of speaking at events some conferences you can get invited or not have to prove yourself so much to get accepted to speak.

Then I was looking at other conferences lineups and saw many repeat speakers from that same conf, often with the same talk, turned me off quite a bit from going to any more conferences, lots of the same, basic content, with not much expertise behind it.