Currently SWITCH in Home Assistant is used both for outlets and other generic switches. Both Google Assistant and HomeKit treats those differently. Introducing separate type in HASS would allow better integration and also better UX on front-end.
The discussion n this topic in architecture repository. Overall having more precise type in the 3rd party integration (HomeKit, Google Assistant) enables device-specific intents. Or in human words - the assistant will understand you better.
Even if there was a configuration for an override when setting up the google assistant configuration to expose switches as outlets in google assistant. I have found in some rooms that the assistant will turn on outlets when I say turn on the lights. (If they are exposed via HA, if they are native outlets in GA they do not).
Or perhaps we have a general override type config for the entity_config then we could configure some switches which control fans as fans rather than switches. (I can do this in home kit in their app)