"Major Tech Site A runs with a skeleton crew, so obviously Major Tech Site B, with a completely different style of interaction and set of requirements, could do so too!" is really not a viable argument.

Furthermore, one of the things that's frequently named as a concern with Reddit is their volunteer moderation; Twitter very obviously needs paid moderators for a host of reasons, and that's something you can't scale with tech. You need actual human people spending their time and energy actually doing that work, in proportion to the amount of content that's being created. (You need more than Twitter has had, in fact, given how many problems there have been.)

You can, of course, argue that they don't actually need that; that it should be all free speech all the time...but you'll get exactly zero traction with me, and with a very large percentage of the public and Twitter's users.