Rylai's vs QSS/Mercurial

So I was playing a game just now as a Varus and had a Malzahar with Rylai's throw his dot on me. I used the cleanse feature on Mercurial to remove the slow, and then it slowed me immediately again.

I understand that mechanically, this is 100% correct and should happen. My issue here is doesn't that mean that if anyone has a dot, Rylai's effectively counter's QSS? Isn't that a little... ridiculous? I'm not saying that the QSS effect should remove the dot, just make it so that particular casting of the dot no longer applies the slow again.