WebGL doesn't allow the dev to write a file to your PC to save, it only allows the writing of a cookie. And cookies suck and are super unreliable for saving.
I just lost a game because webGL allowed my right click to create a hidden context menu in the browser that I then clicked on, forcing the page to go back, and it didn't have a save from the run.
I can't wait until the standalone build is available, either here on itch or on steam. (I already kickstarted)