> Perhaps they could have created a packaged native application for all major operating systems, but in reality that's a ton more work, and a huge impediment for users to convince collaborators to buy/install some native app so they can work on a drawing together.
> What other software are we missing out on because the barrier for interacting with USB/NFC/Bluetooth/Notifications/Background-Sync is too high.
These are quite a bit overstating the problem. The barrier to entry to develop a native app using safari is quite simple, and you can extend safari to do many things, including being spawned by golang and adding other FFI's for javascript functions. The barrier to entry is your willingness to learn and you only see these complaints coming from new developers. Taking a canvas API and implementing yet another collab drawing app is not innovating, it's using an API.
On the flip side, each new API brings more and more surface area for attacks. And if we keep stacking new APIs we don't have enough time to mature and secure up the existing ones. Notice the only example apps given are attempts to replace native apps with web apps.