The sigma 18-35mm 1.8 and Canon 60mm macro are perfectly fine EF-S lenses to pair with a capable high end aps c body. The Canon 10-18mm isn't too bad either.
What if someone already has a lot of EF-S glass? Wants a more updated hybrid body with better video specs like R5 and R6, but doesn't have the money to swap the body + several lenses to FF. The transition to FF if you have 3+ lenses to switch is very expensive. If someone wants to cover UWA, medium and short telephoto range for example and doesn't want to live with only 1 lens on new FF body.
I love my ef-s 24mm and the 55-250 STM.
But i still do not think it justify.