Tanks vs Burst
If you want to talk about pure tank vs burst, then the correct outcome should be a stalemate. If the burst class had enough to kill a tank in short time, then may the Six help all of the less durable classes. Tanks should die to high pressure over time, not so much spike damage. The classes that fill this role are usually DPS classes. Note that these are not the same as burst classes because they deal high damage over time, rather than bursts.
The issue you’re describing is more with bruisers, who are tanky/sustainable and can deal respectable damage. Historically, bruisers have been difficult to balance between having good sustain vs good damage. Ideally, there is a trade-off between the two, but that gets really muddied up when you have modifiers like Might, Fury, Protection, etc. Theoretically, there should be counterplay to this in the form of boon strips and corrupts, but aside from necro and mesmer, there doesn’t seem to be a huge number of classes that have some form of boon hate.