The hidden comments are from people in the Top 1000 by word count (who I usually don't want to hear from but if there is not much content I might click to toggle). The blocked are people I've seen argue with others in a useless way because they don't understand them or because they're just re-litigating or whatever (which I cannot toggle). I think it would be cool if people all published their blocklists and I'd pull from those I trust. Sometimes I open HN on my phone through the browser and I'm baffled by all these responses I got which are useless.
I'm surprised by how much more high quality comment threads are now to me and I frequently find that I want to respond to everyone. It's like in old-school mailing lists or forums where you were having a conversation so the other people are worth talking to.
Attention is precious and I wouldn't want to waste it on boring things. And it goes both ways. I communicate incompletely and there are people out there who get what I'm saying and there are people who need me to be more explicit. I would prefer that the latter and people who find me boring just block me.