Likely yes but not everyone knows how (thinking the non-tech people here) and plus I think it’s nice just to be able to grab a quick extension and be done with it.

I don't know, but I looked at that code and made a userscript and that works. I am glad that it is there because I don't like to use the different style for each one

It is if you have an account. I browse Reddit anonymously and I wanted to get rid of the subreddit styles — hence why I put this together quickly.