Tbf, it is about as buried as a feature can be - in the 2nd of 2 tabs, the 3rd of 3 elements, having to scroll WAAAAAAAAAAAAAAAAAAAAAAAAAAY down past all the already-blocked users and communities to find it. OP should have done their due diligence prior to making such a post, but also it is fairly buried, both statements are true.
This feature has all the classic earmarks of being an “afterthought” that despite its crucial importance in improving a new user’s experience, yet is also extremely rarely used (maybe twice a year?), so it was just tacked onto the existing Blocks page without enhancements that could have made it much more prominently visible. e.g. putting it up at the top, or I note that it has been possible for almost half a century to make a bookmark to something further down in a page - example, and description.
It is things like this that keep Lemmy in a perpetual Beta stage, where new users are turned away due to lack of ease with the UI. Then again, things like Lemmy.World sending duplicates of every single action are also fairly important, and this software is entirely free, and it’s still millions of times better than Reddit, that many of us would outright refuse to visit even if its UI had gotten better (though it has gone the other way instead).
So, it is what it is: somewhat difficult for a non-technically minded person to navigate, but something that the rest of us enjoy regardless.