Why is the Instagram desktop website so unreliable?

All Meta properties generally don't care about (or have active disdain for) the web version. As others have said, this is to drive people to the app, where they can collect orders of magnitude more data and where it is more difficult to block ads or trackers.

The desktop version of Facebook constantly lags behind the app and has weird bugs in Firefox where it will stop loading content, and when anything works on the mobile version of the website I'm honestly surprised.

I’m guessing it’s due to bots. Desktop websites are considerably easier for deploying and managing automations. You don’t need a physical smartphone, just any cheap and capable machine behind a vpn. Things like GPS spoofing are considerably easier and harder to detect. Professional bot farms can take advantage of easy screen sharing and proxying to manage Captchas and challenges, thereby distributing their operation and saving on cost while maintaining scale.

I wouldn’t be surprised if 80%+ of desktop logins are from bots and other bad actors.

Just my two cents on the topic, but I'm guessing that Instagram was never really mean't to be used on desktop – it was developed mobile-first and just ported to desktop when there was a bigger demand for it.

It’s easier for them to get you hooked on your phone than your laptop.

For what its worth I use Instagram via the desktop (windows 10, chrome) every night to view stories for everyone I follow as I prefer the much larger screen (27" monitor vs 6.x" phone). I never have any issues other then it re-muting stories on me if I'm flipping too fast.

It's intentional, to drive you to their mobile app instead, since tracking and advertising are much more powerful that way.

I have also noticed lately, whenever I try to see the comments on the laptop it overheats. I suspect there is something going on to moderate the bot comments in the front-end, which somehow removes them as they load.

I uninstalled the app and use the web version because it’s difficult to scroll endlessly on the web. Something happens in 2 minutes and the page crashes.

Instagram seems to treat all non-mobile users as second class. Their app doesn’t even have iPad support.