A joke I used to tell every coöp student and early-career person I interviewed:
“We only hire senior developers. The trick is, we hire them earlier in their careers.”
The same thing, without trying to be hip:
“Senior engineers are what you get when you hire a junior, give them interesting problems, surround them with people who know more than they do, and wait. That's it.”
https://andrewmurphy.io/blog/ai-didnt-kill-your-junior-pipeline-you-did