I think it depends on which parts of the ecosystem you use. The org publication/export logic has changed a few times in the past 10 years. If you relied on quirks in that in your configuration you would have had to fix your code to repair it after some upgrades.[1]

I have also run into compatibility issues when using older versions of Emacs with newer packages, and newer Emacs versions with older packages.

[1]: I totally did not build my blog on top of a bunch of these quirks. Every time one of them is fixed I'm reminded of the workflow xkcd. https://m.xkcd.com/1172/