Prior to U5 it was a single strike that interrupted your chain.
Post U5, when the off hand mechanics were changed, was when you were seeing multiple procs. Shortly thereafter the bug was noticed. It was recreatable at any time you wished to produce up to 3 procs fairly consistently, sometimes going as high as 5 if you were lucky and timed it just right.
Prior to the bug, it was a fun little broken toy that, while not WAI, wasn't game breaking enough to warrant Dev attention immediately.
Once the bug became more commonly known and widespread, it became time for the Devs to step in and fix it with what you all called a nerf.
It wasn't a nerf. It was a fix.