I'm with you on the usage half: it's planning's job, and analytics/A-B play an important part there.

But I think we're talking past the point that a lot of what you learn building something never show up in any dashboard, because it isn't about what users did, it's what you worked out in the code. That "oh, this whole subsystem quietly assumes X, and the thing I'm adding will break that" moment. By default it lives in the heads of whoever worked on the code and I think is often gone by the next cycle.

I didn't mean to get into who should own what, but I'm trying to ask: the last time you had an insight you felt should be considered next time, did you have a place to put it? Do thoughts like that reach planning, or just dissolve?