...Who's the real expert? The guy who's had all the "training" but has no actual experience, or an old farmer/construction worker/whatever who's had no formal training, but has actually done the stuff?...
Of course, the most expert of all is someone who has both had training and done the stuff.
Let's consider the subject at hand. Folks who actually do house clearing from time to time for a living, do a whole lot of training to do it. They probably do more training simulations than actual house clearing. They seem to think that the training helps. And most of the training is provided by people who also train a lot and probably do it on occasion. And they train people the way they've been trained and themselves train.
How many folks do you know who have actually done any meaningful amount of house clearing and who have had no training doing it?