Really, was it?

Sure, it is not a mastery you should get on your bruisers or tanks at top.

But it was a nice mastery for support tanks (IMHO), maybe also for some junglers which are good at getting assists.

I agree it was somehow missplaced in the defense tree because only tank supports (and maybe certain junglers) benefit from it. But was it that bad that it couldn't be moved to the utility tree? Maybe reducing the effect to assissts only?

The problem was that at most in a normal length match you would get 25 assists. Thats about ~550 gold worth for 3 skill points, deep in the tree for tanks and bruisers, and not supports. While it could have been moved to the support tree, the addition of Pickpocket replaces it and so I guess they removed it entirely. 500 gold late game didn't compare to the 8% cooldown reduction you could get instead (and whatever the one next to it was, I forget.)

inb4 Rioter saying "power without gameplay".

TBH I only used it on def supports because of the lack of gold.

Actually, I had the feeling almost nobody took this mastery.

They took the utility out of the defense tree. Cdr, move speed and gold got removed and replaced with more defense