In this, isn't it more that Garmin has been making sports watches for a long long time? And were given the grace by their customer base to just keep making that particular function better.

You could probably find the same with bike computers. Established brands that have a fairly predictable customer base tend to continue to focus on the thing that they do well. If you are having to chase a market that doesn't really exist, you find half baked features that speak to an idea, but often don't actually deliver on it.

For an amazing example of that last, look at how Amazon is destroying their echo market. If they just focused on "voice activated radio and timers," the device would be very different from the "we are trying desperately to make a new market for our smart assistant."