I don't use twitter, but I could forgive them for being a little slow (if they are?) because of the sheer volume but the reddit app literally grinds my phone to a holt just to load one photo (often, too)
Nothing like that here on HN, and it's some of the best news/comments on the web.
When you need ad revenue, you need user tracking as well as incendiary content. If you can't get people upset so they keep interacting, and then suggest they go and buy some new coffee filters, how will you ever turn a profit.
It's not like Reddit is one guy who lives in the woods, it has so much investor money they need to keep growth up. And app installs are absolutely a fantastic kpi, the more people they can force to install the app the more active installs they can claim, and that makes board members happy
To be completely fair I think hacker News also attracts a much more mature demographic. The mod team does a very good job in filtering out even borderline content.