Dredging telemetry data has a nasty effect of letting you find precisely what you are looking for. There is no way to prove from passive monitoring of telemetry that rouge addons were causing people to abandon Firefox, nor that this measure stops people from abandoning Firefox (Or even stops rouge addons, after all its trivial to recompile firefox and replace a binary, if this becomes a problem is firefox going closed source next, for the users of course). But if you can show two numbers that seem to have a correlation (Like Pirates and Global Warming), you can advance any agenda you care to.

Not to mention this "telemetry" process is entirely opaque, and used to justify decisions like this in a very Ex Cathedra sorta way, where you either accept the conclusions they have made from data you can't see, or be treated like your opinion is irrelevant.

Its a very hostile way to run a supposedly "Open Source" project.