And... Why is that?

Anime can be found on tons of streaming services that don't have comments, like Netflix.

Anime in particular is pretty famous for having its own communities and niche spaces on the internet. If anything, Crunchyroll's comments section seems to me like it's unnecessarily fracturing those communities based on who watches on Crunchyroll vs other methods.

There are costs to maintain and moderate communities. It seems to me like that's adding a good bit of cost to Crunchyroll's business model in exchange a vlrelatively small value provided to a small percentage of their customers. Whereas with dedicated social media platforms, the business model revolves around and only attracts individuals who highly valued that community. With a smaller community like that, it's easier to rely on volunteer mods (like most of Lemmy) or a bit of ad revenue.