I've just skim-read the first link. One thing that leapt out right at the start was the basic rules of the lad's group:
"There are some basic ground rules: explain your reasoning, challenge the proposition, but don't be rude or hostile. Original posters are required to engage and to truly consider counter-arguments."
It would be great if people on Gransnet would apply those same rules, particularly, though not just, on the political threads.
The second link seems, at a glance, to adopt an approach that I'm pretty sure I've seen used quite regularly (deliberately or not, i don't know) on Gransnet:
"They don't attempt to change the minds of people posting hate or argue directly with extremists. Instead they collectively inject discussions with facts and straightforwardly argued reasonable viewpoints. The idea is to provide balance [...]"
Both worthy approaches, imo.
That said, I think Facebook (the only social media platform that I use regularly) is what you make of it.
I first used it purely for keeping up with what my grandchildren were doing - at my DiL's suggestion. (It was she who told me about Gransnet, too.)
Since then, I have joined one open group, which was started by disgruntled customers of an energy company where we could share our experiences, info and advice on how to tackle them. This proved invaluable. I have also just joined a local closed group which is about tackling waste/recycling issues. Again,very useful.
Probably because I am so selective, my own experience of Facebook has been very positive.
If, when browsing, I come across a page/site/group that I don't like, I simply avoid it. Not quite so simple for young people, I'm sure, but I don't really get why mature adults have a problem with this or any other social media platform.