I think you missed my point.
If you block /members/ in robots. txt or block viewing members in permission, there is no broken link.
Sorry, I was responding to the OP, not you.
Bad idea. How would visitors now know that a link doesn't exist? What if they just mistyped something? Redirecting every 404 to the honepage tells visitors nothing.
Did you actually read the link? They are telling you that redirecting a 404 to the home page to avoid broken links is the wrong thing to do.
Also a bad idea unless it was actually content that once existed and has since been removed.
The return codes are a standard like many things on the internet. A 404 is not the same as a 410 and should not be misusded in that way,
Again, I'm not sure you actually read the link?
A 404 indicates that something wasn't found.
A 410 indicates that something which was once there, is no longer.
The article suggests that instead of just using 404 for everything, including deleted material which is no longer there - we should instead be uses 410 responses to give more meaning "there was something there once, so you're not going crazy - but it's gone now, sorry".
Interestingly, a banned user doesn't return either of these - it returns a 403 "forbidden" because you need to be a moderator or admin with the appropriate permissions to be able to view banned users.
So technically, XenForo is not doing anything wrong here. A 403 (forbidden) is arguably more appropriate than a 404 (not found) or a 410 (no longer there), since it was found, it still is there - you just aren't permitted to view it anymore. The message given to users about a banned user is "You must be logged-in to do that". I'm not sure there's much more we should be doing there?
Good SEO is not about what is best for search engines - it is what is best for users. If you confuse your users, then that's a bad outcome.
There would be a difference if the user had been deleted rather than banned - it is this scenario where I think returning a 410 would be better than a 404. "There was once a user profile here, but it has gone".
It's a subtle difference, but I think it would be more useful than simply giving people a standard 404 response to everything that has been removed.