If Intune wiped personal devices that’s a serious failure. BYOD setups are supposed to wipe only the work container, not the whole phone. Either those devices were fully enrolled in MDM without people realizing or someone pushed the wrong wipe policy during incident response. Would be good to see confirmation from affected employees.
This isn't true for iOS at least. You can include device erase capabilities in the MDM profile without enrolling as a managed device.