My interpretation was not to take the specific services so literally but instead to focus on how content has centralized to a few specific places that come with a lot of excess baggage to get at content instead of it being spread out across multiple forums, websites, chats, and so on. There's a lot of infrastructure that goes into powering these services and the advertising backbone for them that simply dominates all other attempts to get any publicity on the modern web. I mean, if you're on iOS, you have multiple integration items for services that you might not even use.
Social media may not be the only use for computers, but there's a lot of effort at all levels of infrastructure put in place to ensure that the devices we use are able to access these few core services really fast while everything else is secondary. Yes, the services are optional - you aren't required to sign up for them and use them, but their presence in modern computing and online just can't be ignored.
Of course they can be ignored, completely, especially on a personal basis, but, in a lot of scenarios on enterprise level this is possible as well. I do most of my paid computing work in a large private network.
Has there ever been more diversity in terms of a customized computing experience than today? No, is my answer. There is something for everyone.
Why should the centralization of some content be a bad thing? The majority of cat videos and other garbage is now on Youtube, good riddance I say, easier to avoid. I say it is easier for me, to get at the content I qualify as good and interesting to me, than ever before.
Man, I used to have to call up random BBSes to explore content... And to reach content beyond my small country, I had to hack business PBXes, so I did not have to pay for the long distance call, as I could not afford it.
I used internet from the beginning, and I do certainly not miss it, there were very little content.
If one is feeling nostalgic, one can revert completely to "neckbeard practices". Go back to newsgroups, use mailing lists and IRC. I am sure OP will feel right at home. But it is also possible to combine these things (modern services), like IRC and Slack. Just one example.
To end, even though we are talking about big services in terms of infrastructure, consumers, and bandwidth, they are a small part of the diversity of the internet and modern computing.
Modern computing is not about services that come and go, it is about what it has always been. R&D, innovation. Modern computing is going to take us to Mars. It's about CERN. Autonomous vehicles, etc.
Social media may not be the only use for computers, but there's a lot of effort at all levels of infrastructure put in place to ensure that the devices we use are able to access these few core services really fast while everything else is secondary. Yes, the services are optional - you aren't required to sign up for them and use them, but their presence in modern computing and online just can't be ignored.