Back in the early 70's when a lot of us were getting released from active duty, the VFW was still run and dominated by the WWII/Korean Police Action "class of 45". They made it clear they weren't much interested in having the Vietnam misfits join their club. I mean imagine, we even thought that our dark skinned brothers in arms should be allowed to join. And, as one WWII vet pointed out to me, "you guys lost your war".
As a result not a lot of Viet Nam vets joined the veterans organizations. That changed after Desert Storm. Class of 45 was dying off and they badly needed new blood. So the desert war vets sort of saved their bacon. The vet clubs even started making it public that they would be glad if a few of the hitherto unwanted Nam types would join up. That's when the "Welcome Home" program started.
Based on my post Viet Nam experiences I have never even considered joining.