I personally enjoy this aspect, as I think it fits the philosophy of the web better. Each slide has an address, because they're separate things. You can also trivially link to a particular slide this way.
I open articles in new tabs, so the going back to HN part hasn't ever affected me.
Each slide should have an address yes but I don't think everything should push do your history stack.
That Git cheat sheet page the was on HN a few days ago. Every time you changed the command it pushed onto your history. I want to click back to HN not back and forth between 2 commands I switched across 6 times.
I was going to comment then but I don't think the site was using push state it is actually browser behaviour.
I open articles in new tabs, so the going back to HN part hasn't ever affected me.