maybe low for western standards, but the majority of devices worldwide cannot display higher resolutions.
hek, even new budget phones today rarely exceed 720p.
anecdote: worked at a cinema and we cast 720p onto the big canvas (10meters wide) because people would not notice a difference to anything higher. overall bitrate and quality of encoding are mostly the deciding factors.
Netflix limiting mac chrome playback to 720p is case in point if true (though I've never heard this). What % of their "high-end" users is this? My macbook has more than five times as many pixels than 720p... I've never noticed this, and Netflix surely recognizes that they don't stand to gain much by streaming higher resolution to most users.
Netflix, of course, does build for videophiles, but I still hold my conviction to the extent that I constantly question the priority of work to make something 1080p or 4K.
I will certainly concede that VR use cases need higher than 720p resolution.