The front-page of HN is a filtered list in and of itself. And I for one actually like the result.
Some people would like to see a different filter and thus create one, because they can. That is indeed not something you can, or should want to, prevent.
But the fact that some people create their own filters is not a motivation to not tweak the HN front-page filter in such a way that the front-page matches the intended goal (pg's goal in this case, presumably adopted by the majority of HN readers, more-or-less codified in the guidelines) as closely as possible.
Some people would like to see a different filter and thus create one, because they can. That is indeed not something you can, or should want to, prevent.
But the fact that some people create their own filters is not a motivation to not tweak the HN front-page filter in such a way that the front-page matches the intended goal (pg's goal in this case, presumably adopted by the majority of HN readers, more-or-less codified in the guidelines) as closely as possible.