A lot of sites removed even tranquil and harmonious comments sections due to fear of legal liability, and also because moderating them was a cost center. IMDB used to have a comments section where film buffs could talk about cinema, often in much greater depth and competence than one would find on e.g. Reddit today. Lonely Planet had the Thorn Tree forums where one could discuss travel with a real community of fellow travel nerds. All gone.

Beyond the decline of longform text due to phone keyboards, I actually think that the restriction of active communication to a handful of detrimental social-media platforms is a big part of why people report feeling more lonely today. Back when the blogosphere and Phpbb forum ecosystems were healthy, people talked about finding friends around the world online.