Sure, you can do lots of things to try to maintain your old Rails apps, but none of them are easy and reliable, especially for those who aren't Rails experts (but may be developers).

Clearly, finding unofficial patches on github and applying is entering the realm of "this thing sure is painful to maintain", isn't it? Especially if you have multiple apps (at different legacy Rails versions) to maintain, and/or you are an enterprise that hired a contractor to deliver an app but has no in-house Rails expertise.

Yes, yes, then you might say "Well, then don't do that, keep your apps up to date, don't take on Rails apps without in-house expertise." Exactly, right. So we agree.