Did I Ruin My hair Transplant by rubbing my scabs off?

Rubbing your scabs after 3 weeks should not "ruin" your transplants.  However, it is important to follow your doctor's post op care instructions.

All scabs should be cleaned with pressured (not gentle) massage to transplant area after 2 weeks.Dont forget that you may wash your head with normal pressure after 20 days , you will not harm grfats .

It is unlikely you caused any damage to your grafts at this point. Its impossible to say for certain but by now they should be pretty well secured and it would some serious effort to damage them. This is especially true if you rubbed the scabs off and didn't pick at them. Transplanted hair is usually falling out around this time so it would be expected for them to be falling out with the scabs.

If you just rubbed the scabs off it is very unlikely that you damaged or disrupted the grafts.  The hairs that came out were probably old hairs trapped by the scab; new hairs should start growing in a couple of months.

At 20 days post op, the grafts would have been fully secure in your scalp. So removing the scabs would not disrupt them. 

I don't like the idea of anyone removing grafts that have scabs on them because we have published a paper in a formal medical journal, that when a person pulls off a scab (crust) from a recipient area in less than 12 days, the risk of losing the graft is very high. See the medical paper we wrote in a major journal below in the web reference that proves my point.