Why not use Bluetooth HID Profile?

[jonasbark]

originally posted by @Makinolo at OpenBikeControl/bikecontrol#68 (comment)

I praise your efforts for trying to standarize the mess handlebar controllers have become, but, at least in the Bluetooth space, there is no need for another standard. There is already HOGP (HID Over GATT Profile) where you can fit all the keystrokes you need, including gamepad controllers, mice and keyboards. They could have used it if they wanted, but they want to keep it closed and proprietary on purpose. I hope to be wrong, but I don't expect any traction of this initiative within Zwift.

Here's why I think the HOGP doesn't fit:

• the OS has ownership of HID devices: apps cannot subscribe to the BLE characteristics or handle custom actions directly
• and this even differs by platform
• HID report descriptors complex, and difficult to implement or extend
• HID does not support multi-device or multi-app scenarios, and it can interfere with OS-level keyboard/gamepad handling (one example is volume keys)
• The profile has no discovery or extensibility model suitable for local app-to-app or controller-to-app communication.