How effective is tracking in increasing user experience over less invasive techniques, e.g. like asking users?
The most valuable information we get is through our forum which is open to everyone regardless of whether tracking is activated or not.
But, people are pretty remarkably bad at asking for things. It's mostly the "better horse" problem. People ask for fixes to proximal issues (make this faster, cheaper, better) and not the big things.
In my own product, we use gtm to understand where in our sign up funnel people fall off. It is a complicated product and a complicated sign up flow. Since people who fall out of the funnel are unreachable, we can't just ask them why. But we can observe that (say) 40% of users bounce off of step X, so let's make that step easier.