One of the big troubles is that if you join a big org you won’t get to do any architecture until you are at least “senior” or “lead”. Maybe that’s not true everywhere, but I have seen a fair bit of it. You need several iterations of “I built a thing” “oh, the thing evolved in horrible ways”, before the instincts for good architecture are developed.

I think Big Orgs need to develop younger promising talent by letting them build small green fields projects. Essentially fostering startups inside the organisation proper. Let them build and learn from mistakes (while providing the necessary knowledge; you can actually learn most of this from books, but experience is the ultimate teacher). Otherwise you end up with 5 year experienced people who cannot design themselves out of a paper bag.

It's not helped by the "jump every 2 years for 20-50% pay bump". They don't have to deal with their own architectural decisions.