I genuinely don’t understand why you wouldn’t use a product like Heap or Amplitude to do this type of tracking
At a minimum, this kind of information is relevant to the people creating products like Heap or Amplitude.
I work at Heap and am just curious why you would still want to implement manually coded tracking.
I think there’s some utility in a company owning an abstraction away from a third party.
Supposing if Amplitude (or Heap) were to ever go under, or if we were to want to change Analytics providers for whatever reason, it would be extremely helpful if the code didn’t depend directly on these third parties.
On a smaller app, I would mostly likely directly use the Heap or Amplitude APIs.
(Late reply, apologies)
You get incomplete, inaccurate data.
It's also fun and good for curiosity to do something on your own rathern than rely on a service and never think about what browsers can do.