So, he was right- there's no point in tying a bumble on a curved hook, but also wrong - that's not what a snatcher is, and I think the question shows what is a fairly common misconception about the snatcher. Certainly many that I see, especially commercially available versions are basically overdressed. Also, when I've seen them in North American media, they're similarly misunderstood, I once saw a Phil Rowley video where he tied a little fat bead head pattern to imitate a scud and called it a snatcher. I'm no pattern purist, but that's a different fly altogether.
Snatchers are palmered flies, yes, but not just palmered wets in the traditional form. I actually think they're one of the very few innovative wet fly styles to arrive on the scene in recent decades. Coming from Loch Leven (I believe) they were originally designed to imitate buzzers high in the water column, the sparse palmer hackle and slim straggly dubbed body slowing the sink rate and create the suggestive fuzz of life that works so well. It just so happens that the form has lent itself well to the colour schemes of existing traditionals.
The reason I think they are a real innovation is that they actually perform a different function to traditional wet styles. When there's a light ripple and fish are feeding just subsurface, they're hard to beat and will certainly out fish traditional palmers that want a bigger wave. They also hold high in the column better than other midge hatch wets like the Black Pennel. So you see, they fill a niche and solve a problem. This is something that most other "new" wets don't as the new patterns are so often just a colour change of a pre-existing fly.
If you have a look at the flies in the picture you'll see easily what I mean. I have taken an Irish pattern, the Paisley, that works pretty well when there are midges around and snatcherised it. The original is a great top dropper when there's a bit of wave and the buzzers are big or balling and getting drowned in clumps. But when the wave goes the refusals will come, enter the Paisley snatcher. Much slimmer and less likely to offend the trout. So don't not tie them because you think they're just a palmer, they're something different and they are a fantastic addition to a wet fly box.
Hook : Wet fly (Kamasan B175) 10-14
Thread : black
Rib : fine oval gold
Body : light olive seal
Body hackle : 3 badger cock hackles palmered
Head hackle : Red cock hackle
Hook : Curved lightweight (Kamasan b100) 10-16
Tag : Globrite no. 4
Rib: fine oval gold
Abdomen : light olive seal, sparsely dubbed
Body hackle : badger cock, stripped on 1 side
Shoulder hackle :red cock
Head : olive seal fur