Sure it is. This is called adversarial interoperability and it is great:
https://www.eff.org/deeplinks/2019/06/adversarial-interopera...
People are going to fix bad websites whether or not their owners want them to. This is exactly how ad blockers work and they solve so many problems with the web it's not even funny. I've posted many times about how we should just stop trusting hostile website javascripts and start writing custom free software scrappers or clients for all of them. I suppose GNU had the same idea. Awesome!
> Who here is going to spend countless hours on that thankless task?
I spent quite some time writing my own JS code for my school's portal because the default site was unusably bad. The results were pretty good and lasted until months after my graduation. If everyone did this, the web would be fixed in no time.
Why should we allow companies and web developers to have the ultimate say in how their sites work? The javascript is running on our computers and we can totally replace it if we want. We are in control and it is time to start exercising this power.