I find that it is completely up to the person wanting to use it! Aslong as you aren’t using it inappropriately then what is the issue? Some horses are good in a snaffle and just need a little more for an extra reminder sometimes and maybe that reminder is the hackamore.
I think the horseworld needs to go easy on the equipment they are using. Direct pressure rather than leverage or pain. Horses weren't even built to hold humans on their back, let alone have metal in their mouth or ropes and chains over their head. The softest option is the best option in my opinion :)
A traditional English hackamore has shanks that provide leverage on the horse's poll and nose. This alone, if trained with correctly, should be plenty of pressure to communicate to the horse clear direction and speed. The additional use of a bit along with a hackamore is just invasive and adds additional, unnecessary pressure to the horses mouth. I personally don't agree with the combination of both - I'm all for the comfort of the horse. Having leverage on the nose and pressure in the mouth just does not appeal to any horse.
With a snaffle? I don't think it's severe at all. I think it's a great tool when you need just a little more breaks but don't want to go up in bit size. I like nose pressure on the ground. No sense in not utilizing it under saddle.