I don't generally like the Twitter model and rarely use it, but I will say that one thing that it does do well, better than the Reddit/Threadiverse model, is very rapidly assembling information about a specific, temporary topic.

Like, the Reddit model is about letting a community assemble over time and letting people find their way there and moderators be chosen and all that. That works quite well for a lot of things, and lets people with expertise in the field arise and all that.

But let's say that there's a huge natural disaster and people are putting up video clips from their cell phones and stuff like that. They can coalesce around a hashtag or a couple of hashtags pretty quickly. Relevant material from people who have had no contact with each other and maybe no time to assemble a community or anything gets drawn together. Other users retweeting content help highlight it. The topic probably won't be active for long. It can be really useful for a rapid setup and teardown scenario.

Of course, that's really mostly following a hashtag, rather than a particular user...

I also dislike the "short comment" model that Twitter uses (though over the years, the comment length has been increased and workarounds added), but one thing that it does help with is to help deal with inexperienced users unfamiliar with quoting etiquette. In email or in traditional forum systems, it's conventional to quote a bit of relevant text before responding to it. This requires knowing syntax for doing so and when it's appropriate. Twitter deals with that by forcing everything to be broken up into bite-size chunks as a property of the system, so someone responding to something is forced to respond to only the relevant bit. I think that that probably helps make Twitter more-approachable.

Mastodon allows you to follow hashtags, which would be like following a topic.

following people is nice if you know these people personally, like from real life.

People that do actual geolocations for the war in Ukraine are basically the primary sources. They figure out where and when videos were taken and do the actual work. Following the topic gets you to some big account that aggregates them

Exactly! I'd be curious to see the reverse poll, asking Lemmy users "Why does nobody use Mastodon?" (and include Bluesky and Twitter in the poll.)

I use Lemmy (and in the past Reddit) because topic based conversation is what makes sense to me. Anytime I try to use Mastodon or Bluesky I lurk for a bit and then just come back here.