Most people see it that way. I did at one time..I think that a master of pool will have much more to learn than master in snooker.
I think that in snooker you have to learn less. More intense on the basics very rarely do you see a crazy bank or kick shot...I have watched about 100 matches of snooker still have not seen a kick shot that someone was making a ball. I'm sure it happens. The point: I think there is more to have to learn in pool.
In no way am I trying to say the game of snooker is easy. All cue sports are tough...
I guess what I am really saying here is...My hypothesis is that pocket billiards is the hardest of all games in cue sports.
I could entertain the notion that 14.1 or One Pocket are as challenging as Snooker, but certainly not 9 ball or 10 ball.
Snooker has so many nuances, it's not just about potting the balls, I've learned this the hard way. It doesn't matter if you are capable of running 50's 60's or 70's, good players aren't going to give you those opportunities very often (ie. maybe once or twice per game if that). Tactical play is huge, to the point that you could be a great break builder but if your safety game is not up to par, a good match player will tie you up in knots. And when you finally do get a shot, your arm is so cold every ball seems impossible.
Safety play is not just about bunting the reds and trying to get back to baulk. You have try to do something on each shot. Perhaps put your opponent in increasingly awkward situations, open the reds a bit reduce the margin for error for your opponents next shot, maybe leave the cue ball on the top rail and send a red down to baulk to keep your opponent from putting you there etc. If you just play safe with out a plan, you'll find yourself in trouble.
In short, if someone walks into tournament and expects to beat the best players because he's run a few centuries in practice, he's going to be sadly mistaken if he doesn't have a well rounded game. I would be surprised if he gets off a 20 or 30 against top local players, maybe less against a top player.