Those are interesting points, but disabling the JIT doesn't really change anything unless it means you can forgo site isolation, and that would be a very risky bet.

It may be that disabling the JIT is fine for users most of the time. However, that is also a tough call --- so easy for your competitors to beat you up with benchmarks, and there will be real use-cases (e.g. emulators) where it matters to some users.

And of course there's a lot more to perf than just the JIT. I barely mentioned JIT in my blog post.