This is very true. Men's pants are tagged with their waist size and will also normally have their leg length on the tag. I've got a fairly big belly so I have a large waist size compared to my height so this is useful.
Having to do the mental mathematics to consider which size I am or having to try on the clothes to get an understanding would be a major pain.
I went to get a couple of pairs of jeans from a Plato's closet recently. I tried 6 pairs of different brand jeans, all 34/32. 4 pairs didn't clear my thighs, 1 couldn't button, the last fit. The cut of the jeans makes those numbers mean very different things..