My opinion on that is the projects scale. Typically people came from a 10+ year Java project of 100+ engineers, to a greenfield advanced hello-world -- of course it's going to feel better and more productive.
Also, as open-source folks say, "rewrite is always better". It also serves as a good security review. But companies typically don't have resources to do complete rewrites every so often, I saw it only in Google.
I've worked in 3 of the biggest rails codebases in the world (Shopify being the last) and I can say from experience that rails legacy monoliths are infinitely worse to work with than some awful, but harmless, sea of struts XML legacy.
I find this really interesting, and meets my (limited) Rails experience and (extensive) Java experience:
I found it hard taking over an existing Rails project - it felt frail to me, that any small change might have unexpected consequences.
Whereas when I've taken over Java projects - or come in late to an existing team - I felt quite confident getting started, even if it is a bit of a mess.
Also, as open-source folks say, "rewrite is always better". It also serves as a good security review. But companies typically don't have resources to do complete rewrites every so often, I saw it only in Google.