I had this issue recently where I wanted to revive an old side project I worked on a few years ago. The front-end was written with React + Redux + Webpack, which I assumed I would still be able to get running today, but it ended up turning into dependency hell (even though there were version numbers in the package.json, npm doesn't lock to those versions?!?).

The backend was written in Go, and I just ran go build and it worked without problems. The fact that it just worked without me having to change anything shows how important backwards compatibility is to that community.

The past few weeks I've been working on a backend Typescript project, and the number of packages I've seen that don't use semver or any similar versioning system makes me cringe. I even saw one that wore this as a badge of honour in their README :s If you release a library and you don't have a sensible versioning system, you are just making life harder for your users. (I'd argue for a CHANGELOG too - the GitHub releases section doesn't count)