But I've always thought a team of generalists beats a team of specialists, which is swimming against the current tide.
Considering nearly any situation your team encounters, junior people, experienced people, and very senior people are likely to take different lessons for it, because they have different perspectives on what happened and what could have/should have happened.
To me, a "same year of experience, 30 times" person is someone who runs into similar situations over and over, but fails to grow in how they understand and react to them. This is true of architectural issues, interpersonal issues, schedule management issues, ... everything really.
Technology stack isn't so important here. If anything I expect the experienced people to pick up a new stack faster, if they've done this before, all else being equal.
I'd expect insight and ideas from a 20+ year developer I'd never dream of asking a junior (< 5 years), and if you don't get them - you're probably looking at someone who has repeated many of those 20 years.