Telemetry (if it’s truly telemetry) is nowhere close to “tracking”. People conflate the two all the time. One can provide useful, anonymous metrics (e.g. “user enabled feature X”) without doing anything but incrementing the counter for “feature X”.

The “Firefox Problem” is that all the power users disable telemetry, so all the “cool” features that power users like (but never get used by “regular people”) get ignored or removed instead of improved because, according to the metrics, “nobody uses them”.