And nobody wants to do both (or has the incentive to do both). I'll do sorta-both but probably in an informal way--e.g. article that grew out of a talk--or vice versa.

I've been doing annotated versions of my talks for a while, takes. Few hours of extra effort but greatly increases the impact the talk can have: https://simonwillison.net/tags/annotatedtalks/

Maybe it's because I write a lot but I reached the conclusion that if it makes sense to do an article/blog, I should do so rather than speaker notes--which make sense in handing off a presentation to someone else in a company setting but I'm less sold on, in general, as a personal thing.