I've seen a bunch of "hail damaged" slate, clay tile and extruded concrete tile roofs over the years. Very few of them have incurred hail damage. Most are repairable as not all of the slate or tiles get broken. Comp shingle roofs are asphaltic and "soft." If there is hail damage then the entire roof will most likely be damaged and require replacement. Singling out 500 shingles out of 6000 for replacement is a fool's game.
To be fair, I've never seen a single slate roof that has been tested for impact resistance. Most clay and extruded concrete roof tiles used in the Texas (and hail prone states) are tested per TDI's impact resistance methodology and have a rating.
Yes, unscrupulous storm chaser roofers will press this claim and involve IAs and refer HOs to plaintiff's attorneys. They have nothing to lose and everything to gain. They don't do new construction slate or tile roofs; so they don't make money there. Comp re-roofs are good but a volume game. Large houses with expensive slate or tile roofs with lots of copper flashing techniques are whales when it comes to scopes of loss and potential payouts.
The real problem for the HO is they will get a storm chaser under contract and that fool has no clue what he is doing with a product like slate or clay / concrete tile and then the trail of tears begins.