I don't like the mob thing either but it's how large group dynamics on the internet work (by default). We try to mitigate it where we can but there's not a lot of knowledge about how to do that.
To explain a bit more:
On the one hand, you need a critical mass of people to have a discussion. On the other hand, large group dynamics seem to be a problem.
HN is generally many multiples larger than the critical mass for the former, at least on the front page. Attention drops off a lot if you go further.
So as an experiment, you could do something like 'rendezvous hashing' to show each user a random 10% subset of submissions. (If you want to gradually introduce it, run the experiment on 20% of the users only, but show them a 50% subset, so that each of the longer tail items still gets 10% of total users? You can play with the numbers.)
You could make this opt-out, too, so that people don't create ten accounts in the hope of seeing everything. Direct links would also still work.
What's not clear to me in your comment is what we would be testing for. If you're going to A/B test different front pages, what's the fitness function?