And the only platform that works on my windows desktop, macbook, work Linux machine, Android phone, iOS tablet, Xbox, TV, and watch with an "install time" measured in seconds, a top of the line security sandbox system that takes very little effort from the user to configure correctly, a very visible badge telling you if the connection is encrypted or not, and an incredible amount of easy customization by the user which is so powerful it can completely change how an app looks with zero input or permission from the app creator.
Reliable low latency transmission of audio and video is also one of those things that looks easy unless you try to actually get it working in practice.
I think the reason is that if we ever get a real solid web platform it will start competing directly with all of the vendors proprietary operating systems. So there are billions of dollars worth of reasons to maintain just enough incompatibility and spotty featuresets.
I mean I have been waiting for two decades for it to happen.