Actually kinda to the contrary BT is extremely back-supporting. It adds/removes features so slow that it’s too boring. That’s why I left my BT expertise at the start of my career and moved to app development (it was a mistake in the hindsight but that’s another story).
Sure, it's backwards compatible in theory. In practice I haven't had any device that kept working reliably with zero issues through every Android update and every phone upgrade. Including very important ones like Tesla's phone key. Even Pebble wasn't flawless at the very beginning, but it got good fast and hasn't stopped working since the company went under.
