But it's not new stuff, mostly. It's just the same old stuff in a new package.

Yes, indeed that's true. But they get upset if you tell them that their genius new idea is just an old idea they didn't know about ;-)

That's precisely why it's not really that big a deal to learn the new stuff. If you know the fundamentals, learning the new tech is fine. It can be a little daunting at first but once you familiarise yourself with the new jargon and what value the practical differences bring you can apply your knowlege very productively.

No. Learning a new ecosystem is far more work and takes far more time than (so to speak) learning a few keywords of a new language.

Aren't you contradicting yourself?

Why? It takes time to master new ecosystems, even if what they offer is a complete duplicate of what already existed.