I don’t understand your argument here. Google has been working on fixing the their own crashes with the data they have right now. Why would they turn it on for everyone else while they do that?
They have already fixed nearly all the crashes in the base OS. The issues we face are almost entirely regressions in new versions. They fix them consistently but they aren't stopping the regressions getting into releases because they don't use MTE in production.
Regressions in Android because they aren't doing enough real world testing with MTE or HWASan builds. They're clearly testing them via CI and fixing those issues but in real world usage more issues are uncovered which often slip into releases then get fixed in another release a few months later.