I think another reason why it feels like there are much more beginners in frontend than backend is that the ecosystem moves much quicker and there aren't any lo

I think another reason why it feels like there are much more beginners in frontend than backend is that the ecosystem moves much quicker and there aren't any long-term established frameworks/patterns yet. You can't build as much experience on something that's constantly a moving target. (browsers themselves move and change what patterns can be built and whether the existing patterns are worth pursuing vs starting over) In constrast, on backend, experience with an MVC framework and SQL database from 10 years ago (even 20 for databases) is just as current today. The APIs might change superficially but the general pattern is the same.