I strongly disagree with that. Best developers switch many jobs - that's how they become great - by working on lots of different stuff and learning all the time

I strongly disagree with that. Best developers switch many jobs - that's how they become great - by working on lots of different stuff and learning all the time - there are very few full time positions where you can continuously learn and actually do new things all the time and don't become a nuisance for your co-workers. They also start their own startups, fail, and go to job market again.