[2020] Wintertide brand seems pretty terrible compared to current cold DoT skills

The mechanics aren't very clear, but the maximum number of brands you can have on an enemy is 3.

If the damage stacks but the activation doesn't (so you have 3 brands which each deal damage, but only activate as a whole every 0.25 seconds), then it has a highend damage of 2400 dps. However, this requires you to hit 20 stacks, when the default numbers give it 8 stacks. To reach 20, you need to invest in mechanics which do nothing for any secondary DoT skill (and nearly every cold DoT build uses at least 2 DoTs).

The other option is that the brand activation stacks, but the damage doesn't. I can't believe that's the case, since it leaves you with and 800 dps cold DoT, which is barely half of vortex's damage.

Unless both the activation and damage stack, the gem just seems significantly worse than anything we currently have.