An Educated Mech. would never go for removal of thermostat valve. The silliest mechs go for its removal.
Removal of thermostat valve causes engine temperature to not reach it's required level. As a result the metal parts do not extend to there maximum OEM temperature range specified by the car manufacturer while they build their engines.
So it is way silly if you're mech. rips of the thermostat valve. Your'e mechanic skills are 0 if he is removing that....
My mechanic uncle has never removed thermostat valve, infact he is very much against doing this job as they are designed for the engine keeping something in mind by the manufacturere....
So for all you car users, if you're mechanic is going for direct fan after overhaul, do not let him tamper with the thermostat valve, and once you're done with the engine RUNNING stage, fight back with your mech and get the auto-fan circuit restored back because that is how the engine was designed to work, not with fan running all the day...