Earlier quoted context omitted.
A lot of non-free software is written in Javascript and runs on webpages. If you want to avoid using non-free software you have to disable Javascript on many websites. Ideally the Javascript would be freed, but making it optional might be a more feasible goal.
I've always been a bit confused by this take, because the most likely alternative to having proprietary code in the front-end is to have proprietary code in the back-end. It's not clear to me why I shouldn't tolerate closed-source Javascript that I can nonetheless inspect, archive, and edit on my own machine, but I should tolerate a closed-source SaaS backend that I can't inspect, archive, or edit. Of course propriet…
The idea behind 'free' software was that you should have access to/control of the software running on your devices, not everyone else's. It was originally a pragmatic solution to a problem, not an abstract ideology that it's morphed into for some.
[1] It's up to the business in question to care about the software running on their computers.