Recently I read Avoiding Emacs bankruptcy, with good financial habits (via). To badly summarize the article, it suggests avoiding third party packages and minimizing the amount of customization you do. As it happens, I have experience with more or less this approach, and in the end it didn't help. Because I built my old Emacs environment in the days before third party Emacs package management, it didn't include third party packages (although it may have had a few functions I'd gotten from other people). And by modern standards it wasn't all that customized, because I didn't go wildly rebinding keys or the like. Instead, I mostly did basic things like set indentation styles. But over the time from Emacs 18 to 2012, even that stuff stopped working. The whole experience has left me feeling that Emacs bankruptcy is inevitable over the longer term.

The elements pushing towards Emacs bankruptcy are relatively straightforward. First, Emacs wants personal customization in practice, so you will build up a .emacs for your current version of Emacs even if you don't use third party packages. Second, Emacs itself changes over time, or if you prefer the standard, built-in packages change over time to do things like handle indentation and mail reading better. This means that your customizations of them will need updating periodically. Third, the Emacs community changes over time in terms of what people support, talk about, recommend, and so on. If you use the community at all for help, guidance, and the like, what it will be able to help you with and what it will suggest will change over time, and thus so will what you want in your Emacs environment to go with it. Finally, both your options for third party packages and the third party packages themselves will change over time, again forcing you to make changes in your Emacs environment to compensate.

In addition, as the article implicitly admits, that a package is in the Emacs standard library doesn't mean that it can't have problems or effectively be abandoned with little or no changes and updates (for example, the state of Flymake for a long time). Sticking to the packages that come with Emacs can be limiting and restrictive, much like not customizing Emacs at all and accepting all of its defaults. You can work with Emacs that way (and people used to, back in the days before there was a vibrant ecology of third party packages), but you're being potentially hard on yourself in order to reduce the magnitude of something that's probably going to happen to you anyway.

(For instance, until recently not using third party packages would have meant that you did not have support for language servers.)

My view is that in practice, there's no way to leave your Emacs setup alone for a long time. You can go 'bankrupt' in small pieces of work every so often, or in big bangs like the one I went through (although the small pieces approach is more likely if you keep using Emacs regularly).

I don't think this is a bad thing. It's ultimately a choice on the spectrum between evolution and backward compatibility, where both GNU Emacs and the third party ecosystem would rather move forward (hopefully for the better) instead of freezing things once something is implemented.