Clearing room to room against an untrained force or unprepared might be one thing but when you have to go up against a highly trained and well prepared force then the dynamics of the battle field changes.
Currently our forces have been lucky that their foe has not had the training that a more formal military would have, not saying at all that it is still very dangerous job.
If our forces or any force for that matter had to go up against a well trained very disciplined military force.
example; the Parliament house in Berlin Germany 130-150 Germans barricaded in the building, 20,000 Russians lost their lives taking just that one building.
Yes the more training our forces have the better, I agree, in my days toss in a grenade followed by a Sten bolt locked back, and the trigger wired back as well, after it ran empty then we would go in
We also had more then one clearing team in a building and we would try to enter the building from the highest level that we could better to let the enemy run down and out then to trap them on an upper floor, and we would blast through the floors rather then use the stairs.
Yup, been there, done that, 27 year of service