If they introduce targeted ads or up-votes/interactions could be monetized in HN, even with the the same community, you would start to see the deterioration IMHO.

Cool headed, interesting or curious do not generate enough click through as much as controversial, conspiracy theory, outrageous, hateful, etc. It's interesting that there's no ban on political or controversial content in HN but still, you don't see them take over the platform. The incentive is simply not there!