This is why browser gaming isn't taking off. User interface quirks.
Even in native you're likely to trigger Windows' "sticky keys" feature by pressing shift repeatedly (a standard keybind in many games). Back in the day, games used to crash on alt-tabbing so sticky keys killed your game until disabled.
Microsoft's xCloud only streams controller games for now, and I think that has provided an exceptional user experience early on. You can select the game in your browser, and pick up the different input device while the stream loads. Once you're done playing, put the controller down and Ctrl-W to close the tab and go back to the real-world.
Even in native you're likely to trigger Windows' "sticky keys" feature by pressing shift repeatedly (a standard keybind in many games). Back in the day, games used to crash on alt-tabbing so sticky keys killed your game until disabled.