Exactly this about Instagram and Facebook bother me a little bit too, and here is something that most people also don't experience:

I sometimes use a VPS from a popular cloud provider as a proxy for my web browsing. I frequently get asked to "Prove I'm not a robot". This happens on all kinds of sites, including Youtube, Paypal, some government sites, etc. It is annoying enough, but Facebook as well as Instagram won't let me see _anything_ without logging in (which I don't). So can't even check the Lunch menu for a local restaurant on Facebook over this proxy.