Due in part to the excellent UI and user-friendly reading experience, both on that mobile app and in a browser on my laptop, HN is the site I visit most often every day for a pleasant break to learn new things.
Reddit on the other hand is something I look at maybe once a month, where I'm reminded each time it's disorienting and hard work to use, so it's not somewhere I go to enjoy a calm read. So for me Reddit is just for finding specific information from a search result then leaving.
The Reddit UI has a lot to do with that. It ties to the "randomness" of the content. HN content also has randomness but because of its UI you can skim a lot in seconds so it's easier to pick out things of interest with low stress and just enjoy them.
Typically I glance through the top 100 to 150 headlines of HN to pick a few of interest, several times a day. It takes about 10-20 seconds to read those headlines, and to know I'm done - which is very different from scrolling-oriented sites which deprive the reader of perspective. I can see how this might be different for people who cannot skim text quickly or who find that difficult, or who are trained to infiniscroll through things showing only a tiny number of large cards on the screen at a time. The latter is how you destroy perspective.
I had no idea it was gone from the Play Store or not updated in a long time - or maybe I forgot soon after installing. I'm using the version installed via F-Droid.
The good news is it still works :-)
It has a lot of forks. I wonder if anyone's developed it more.
https://play.google.com/store/apps/details?id=com.simon.harm...
I'm typing this comment on a third-party app (Hacki) I'm trying out for the first time, so that's another option.
The arrows could be better, but they aren’t actually an essential part of the site from an individual user point of view. They are there to help HN. If they decided that getting this help from mobile users isn’t a priority, that’s fine.