As Patrick said, definately do not feed waxys as a staple.
There are a lot of myths about mealworms - most of them are not true. They wont eat your leo from the inside out
and as long as your other husbandry parameters are ok and you are feeding appropriately sized mealies (dont feed huge mealies to little Leos) then they will not cause impaction.
As a matter of fact, Ron Tremper feeds all his Leos exlcusively on mealworms with no problems.
It often comes down to preference too, some Leos, particularly babies prefer crickets and roaches because they are more active.
-----
1.1 Bearded Dragons
2.2 Leopard Geckos
1.0 Uromastyx (Mali)
1.1 Corn snakes
0.1 Mexican Black Kingsnake
1.0 Bairds Ratsnake
1.0 Rosy Boa
1.1 Green Anoles
1.1 House Geckos
0.0.2 Flying Geckos
0.0.1 Red Eye Tree Frog