OPTEMPO has little to do with it, if anything it keeps people in longer. If you go to www.armyranger.com, a lot of those member signatures will say : "1/75 92-94", "3/75 88 - 89".
Also, back in those days, the Regiment strictly adhered to Abrams Charter...so guys had to leave, they didn't have a choice in the matter. Where as, today you can stay until you fuck up bad enough to get kicked out, or elect to leave.
It's just the nature of the beast (lifestyle), that wears people out.
I agree completely, it's the reason I am where I am right now, and I'm sure many others as well.
One advantage SF has over the 75th, is that when guys get tired, they have waaaay more instructor and LNO billets available. In the 75th, you either have to leave the Regiment, or compete for one of the highly competitive instructor slots at the ROC. Those are some interesting stats on how other countries conduct business.