Even if telemetry is useful (this is a rare example - the vast majority of telemetry is either useless or actively works against the users), it's still a breach

Even if telemetry is useful (this is a rare example - the vast majority of telemetry is either useless or actively works against the users), it's still a breach of privacy and confidentiality (crash dumps - which are necessary to investigate/reproduce such bugs - can contain highly confidential data including passwords or session cookies). > but only if you collect the data. If the problem is impacting the user and they want it fixed they'll happily tell you. This bug (which causes crashes) would've been investigated just as well by asking users "Firefox has crashed - send bug report?", while giving the user the choice to decline if they had sensitive data in the browser's state. Obviously nobody in their right mind should opt-in to generic telemetry because all the "product improvements" excuses never panned out - in the last decade software has only become worse, more annoying, and less feature-full, so people are making the rational decision and are not opting into something that's not actually benefiting them. But opt-in telemetry in specific cases where the user actually has a problem like this occurrence can work just fine.