I think there is more diversity than you might think.
Arnold Palmer was 5' 10". Jack Nichlaus was 5' 10". Gary Player was 5' 6". That's four inches difference but in many minds Player almost seemed a midget compared to Jack and Arnie.
Yet today, while you may think the guys on the tour all look alike, there's a fair amount of diversity. The top ten finishers in the PGA Championship spanned a nine inch difference in height (from Francisco Molinair to Thomas Pieters). That's a pretty broad range of cookie cutting.
1. Brooks Koepka 6' 0" :
2. Tiger Woods 6'1"
3. Adam Scott 6' 0"
T4. Stewart Cink 6' 4"
T4. Jon Rahm 6' 4"
T6. Thomas Pieters 6' 5"
T6. Francisco Molinari 5' 8"
T6. Justin Thomas 5' 10"
T6. Gary Woodland 6' 1:
T10. Rafa Cabrera-Bello 6' 2"
T10. Tyrelll Hatton 5' 9"
For some reason, I think the TV cameras seem to project the guys as all looking about the same height. It might have something to do with the way that the telephoto shots frame them.
Yes the above guys all were pretty lean, but you also have a few guys who lap over their belts a bit ala Beef Johnson. Patrick Reed, Jason Duffner, Pat Perez, Kiradech Aphibarnrat, Shane Lowry, etc.
If you dig just a bit, the diversity is there.