I'm not sure what sort of API is exposed for use by other programs, but on macOS, QuickTime will show a USB-connected iPhone as a video capture source to record the screen. I don't know if other software can take advantage of it though.
tired: your system administrator requires you to restart your browser in the next 48 hours
wired: hey do you want all the new emojis your friends are already using?
otoh, there are a _ton_ of insecure sharp edges most frameworks protect against that won't get noticed if "performance" and "ease of dev" are the only things ppl are paying attention to.