Sounds like you haven't been working long enough to forget your decisions, which you WILL do eventually. In such cases, where you're looking at code you wrote 10 years ago and you find a weird line, when you view the git blame and read the commit message, you'll be very thankful that you explain not just "what" you did, but "why" you did this, something an AI will have a very hard time doing.
You don't have to if you don't want to, but if you think "this commit message is just a summary of the changes made", you'll never write a useful commit message.
I’ve been working in the industry for two decades, and I think commit messages is not the best place for storing decisions and associated context. I personally prefer ADRs.
Two decades and you don't see any value in writing down what's currently in your head?
Anyhow, ADRs are good, but they stand for Architectural decisions, not every decision is at that level.
In general, if there's a better place to store explanations, do use it, but often, in many projects, commit messages are the least bad place; and it's enormously better to write there than nowhere at all.
Line comments work pretty well for explanation storage. :) Almost every programming language support that feature.
They can sure be good, and are often indeed a better place, but unfortunately most people don't want too many lines of comments in the code.
We sure should have better tools to handle code annotations, but commit messages are a not too bad fallback until we get them
That’s why you put the comment in the code
comments rot as the code changes around them