Apparently it didn't used to suppress DoTs but because of that Cloak kept breaking so they suppressed DoTs in order to make it work effectively. I don't like it either.
This feels like a bad idea but that maybe because the timing couldn’t be worse. We are at least for another two weeks in a major defile/DoT/sload meta and with only sloads scheduled to change in a meaningful way I think it would only empower the meta further and make the play style of cloak based StamNB more countered than it already is.