I find your ideas intriguing and I wish to subscribe to your newsletter.
More seriously, yes, if you were starting a browser completely from scratch, this would probably be a good approach. There are some subtleties, but probably nothing that couldn't be solved with some elbow grease.
If anyone is seriously interested in exploring this direction, one thing that would be very interesting is a port of piet-gpu to run on top of WebGPU (it's currently running on Vulkan, Metal, and DX12). I've done quite a bit of pre-work to understand what would be involved, but don't personally have the bandwidth to code up the WebGPU port. I would be more than happy to work with somebody who does.