The curious part is that this is the opposite of how entities in Home Assistant have traditionally been configured/organized.
For countless versions, entities have been organized according to their domain such as
lock, etc and not the underlying integration that supports the entity. It’s been the responsibility of the
platform option to indicate which integration is used for a given entity.
It was the recently revised Template integration that (I believe) was first to diverge from this long-standing organizational model. Now the MQTT integration has followed suit.
Would you happen to know the rationale for this change of organizational structure?
FWIW, I am unaffected by this change because I use MQTT Discovery (via scripts) to define all MQTT entities in my system (sensors, locks, binary_sensors, lights, switches, etc). According to the documentation, the new method of defining MQTT entities still doesn’t allow you to define devices (whereas you can with MQTT Discovery).