Hi Max,
Good point but not easy to answer. All services can be viewed with a Free Software browser but e.g. Facebook tries to convince you of downloading the non-free Messenger app (you cannot even write FB messages on your mobile browser anymore IIRC). LibreJS may also warn its users with most of these services' sites. Is this already Free Software unfriendly?
If there's a way to connect to the service with Free Software and it gives you access to the features the service offers, then that's fine for me, as long as it's not overly burdensome to do so. I know, it's not a black and white :-)
But that some services work *better* with non-free software, I wouldn't pay much attention to, nor that they offer non-free software for download. The same applies to a lot of Free Software, where the developers would be really keen for you to "upgrade" to the proprietary "enterprise" version.