Latency is the real killer. I used HughesNet satellite internet while travelling for a while and it has a 650ms round trip. Even sites built by talented and well compensated engineers would sometimes be completely unusable. For example, YoutubeTV used to download the video data in tiny little sub 1MB chunks, each from a seemingly separate CDN endpoint. The result was that each chunk needed a DNS roundtrip and then another one or two for SSL handshaking so it would take at a minimum 1.5 - 2 seconds to even start downloading the data. Needless to say, it was not usable.
Moral of the story - latency and roundtrips are the devil and some users have it extra bad, but if you make it work for them, it's going to be amazing for everyone else too.
Moral of the story - latency and roundtrips are the devil and some users have it extra bad, but if you make it work for them, it's going to be amazing for everyone else too.