Clarity on Swain Nerfs

I'm specifically talking about the 2 second lockout on re-casting his ult that was added in 6.13. This feels like an attack on his "Quality of life" more than a balance mechanic.

Early in the game, Swain generally suffers from lack of wave clear and is pushed in by his lane opponent, and a method to assist last hitting under the turret was to use the old Q as a proc of damage to prime caster minions etc. With his Q rework, he can't effectively use it under turret to strategically last hit.

Another method of last hitting under turret was to cast swain's ult, and turn it off immediately so one round of ravens flew out and hit the 3 caster minions. This would "prime" all of them so they could be last hit after a turret shot. With this 2 second lockout, this mechanic no longer remains and swain has no reasonable way to last hit when he already struggled from the slow auto attack animation.

So was Swain being able to turn off his ult quickly actually an abusive mechanic compared to other champion's kits that it had to be nerfed? I just need some context on it as I say goodbye to my favorite champion again.