Alphabet, Google and to a lesser extent, YouTube, have a lot of ressources, but they might not invest it in this direction. A friend worked on a team responsible for understanding creators, recently, and it was alarming how few people were involved. He left because it was poorly managed. They barely scratched the surface on engagement, not even able to measure the lack of consistency of audience engagement (the biggest point of contention of creators).
They likely have fewer people dedidated to fighting spam overall, let alone in comments, than you’d expect. This is a delicate interaction to highlight because it’s both account creation (accounts that don’t upload videos, so they likely aren’t prioritised) and editing their identity, something no one cares much at YouTube (you get plates if you matter, that’s operations); all the bad things happen off YouTube…
The other comment about adversarial interactions with spam is key --and likely more important-- but we need to remind everyone (including people on HN who likely have experienced this at their job) that “it’s a large company” doesn’t translate to “they have large teams working on this” but “they have many other problems prioritised over this”.