What you see as nonsense might make sense to others; you can't just conclude the complete meaning of someone's statement based on your own personal point of view. Here in this forum, everyone is entitled to their own ideas; you can't contribute more than you don't know.
 
I won't argue with you about a few people posting or making off-topic comments because just because I'm a higher rank member does not make me perfect if I go off topic or my idea towards a particular issue is not in line with what's being currently discussed. Anyone can call me to order it's not based on rank.
 
Another thing is that a legendary member, which you might also see dropping a few topics that do not actually match their rank or their comments are far off the mark, has been caused by or based on two reasons:

1: the member acquired that rank by opportunity and did not really merit it; what I mean is that they might fall among those that were airdropped merit when the merit system was introduced. Because earning enough merit and activities to reach a legendary rank is enough time for one to familiarize himself or herself with broad knowledge, It's not by force to always contribute to a topic, so if they don't have anything to say, they will avoid the thread.

2. The account might have changed hands; the real owner built it to that level; if someone who's supposed to still be learning around the forum and outside regarding things now happens to get their hands on such an account, irrelevant posts might likely occur.
But to be clear to me no one's comment is actually completely useless some people will still take a few point from it why your will be busy criticizing it. In your thread, for example, not everyone will have to support it; few will see it as completely useless.