In my experience this affects techie users just as much. Especially when there is a UI that has been crafted and slowly perfected over the years, and where any remaining idiosyncrasy has long been learned by the user, changing that UI has profound negative impact on the productivity of anyone using the platform.

I have rarely seen UI changes where users were genuinely excited to have a new UI with the understanding that they'd have to learn new paradigms. Most web apps should still be Bootstrap apps, but of course then you can't put that on a giant dashboard wall at a conference ;)