Fitbit isn't really made for serious fitness enthusiasts. If you look at its feature set and design, it's trying to give the average person a way to get data about how fit they are in the range between not fit and average. The sleep tracking, water tracking, automatic workout tracking, and other simple features are more for the average person than for a marathon runner. So it doesn't surprise me that they don't support chest straps because most people don't want to do zone training, they just want to know whether they're getting exercise that will EG condition their heart.

The problem is, you get a Fitbit as a casual person just getting into exercise - and before you know it, you've outgrown Fitbit!

That's not a great business model. They should have devices that either scale with you, or different models with feature-sets that target different ranges of users.

The people that are active and stick with fitness tracking are exactly the ones that are most likely to purchase new devices over time - either as replacements or upgrades. Instead, they switch to Garmin or some other more "serious" fitness tracker. That's a crying shame for Fitbit... the original fitness tracker.

Supporting chest-straps, or selling their own chest-strap, doesn't mean a casual users needs to buy one. But it does mean a growing serious fitness enthusiast can continue to use Fitbit, buying new devices over time.

From my experience, Fitbit still has the most polished App. It's a darn shame you can't get more out of Fitbit devices though.