We actually agree with some of the points made above, but we'd like to add the following commentary...
Encrypting email while making it more usable than PGP is hard. There's no getting around that. Web crypto is always going to have some shortcomings, but web mail is on the rise, and at the end of the day, web crypto is better than no crypto.
That said, we have been working for some years towards moving ProtonMail encryption entirely to the local environment using our Bridge application, which will be released soon. There is also extensive R&D being done on end-to-end authentication and ensuring key validity.
You are correct in that it is not a level playing field. This is why the tech industry is fast becoming an oligarchy or even a monopoly, owned and controlled by a few big players. However, we think that not playing is taking the easy way out, so even though the game is 'rigged' against us, we have a great team of engineers who have decided to play anyways.