Because he's building native JS games already. And they likely work in Safari. It would be a step backwards, unless he wants to publish for desktop/mobile as well. I even found Godot's desktop export to be less performant than things I've built natively for the browser when lots of onscreen objects are involved. The only way I found to get around that was to use Godot's C++ extensions or modules, which defeats the object of an engine like Godot. Unity, Defold and Unreal proved unsuitable for other reasons, and the most viable platform for building games for desktop and mobile after working with JS and WebGL turned out to be Raylib. I can only share my experiences, everyone should do what I did and shop around, but if you're happy working in the browser, there is no reason to move away from native technologies.