My experience is exactly the opposite, most non-techie users hate pointless UI changes. They couldn't care less about some new design paradigm but they care a great deal that some action they've been using for years has now been changed out from under them. For most people a computer is a tool and they care far more about what they can do with the tool than seeing the tool make itself the center of attention for a time.
Redesigns are often self-indulgent. Designers like that they get to do something new, employees who stare at the same software every day get to change things up, and managers get a highly visible change they can point to as evidence of their "impact". What's best for the users is often not a top concern.
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 ;)
Most people who are working in tech or who are tech literate want a UI that's readable and easy to use, with minimal fluff because they use it extensively
Most people who don't really care about tech that much don't like UI changes like you said because it means relearning what they know
The ones who love flashy new UIs are the tech enthusiast, the ones who love tech but use them on a surface level only, they are also the ones who will buy new, unproven tech and care little about privacy issues or open source. My guess is it makes a lot of sense for big tech groups to target them instead of the grey beards who won't be convinced anyway, right as they may be.
Redesigns are often self-indulgent. Designers like that they get to do something new, employees who stare at the same software every day get to change things up, and managers get a highly visible change they can point to as evidence of their "impact". What's best for the users is often not a top concern.