I gone through a lot of hosting service providers and unfortunetly cannot find a single one that can be used without running nonfree programs, all of them require loading bulky JavaScript apps.
I know of Codeberg Pages for example, but it is not suitable for business use.
Major browsers are downloading and running programs automatically in the background without knownleage of user. If you block this those sites won't work, because those websites are just blank and you actually run an app.
Your problem is that there is JS code running in a browser?
The way they describe it has me baffled. At first I assumed they were referring to PaaS like Heroku or Vercel and somehow weren't aware they could just get a barebones Linux VPS.
But no, going by the response they're complaining because VPS provider websites require JavaScript to function?
OP you know you can clear cache after and bam, all the locally cached JavaScript in your browser is gone.
If you do happen to be referring to PaaS solutions, just go barebones and use SSH to connect and configure it.