Because you have to maintain the app against known vulnerabilities. And in even a single year previous version of out app had multiple gems with vulnerabilities having to do a major version upgrade and I had to scrap the whole thing because older gems with fixes where unavailable or didn't build on modern rail/os

The whole ecosystem is frankly a mess, you need to stay bleeding edge all the time to have a chance to long term maintenance and suffer any capricious api update each of your dependency might have because staying on old release and relying on backports is not worth it.

I'm not paid to clean other people libraries. If the idea of open source is that, then no thanks. Core business is not maintenance and costs like those do kill startups.