That's a questionable point of view. It's like saying that surgical operations are painful, that is obviously untrue in case if they're done with a proper analgesia or anesthesia.
Drowning causes unconsciousness by making the blood oxygen saturation low enough, but so does gas asphyxiation too. If you faint from gas asphyxiation first, then you no longer need to wait until drowning makes your blood sufficiently oxygen-deficient for losing consciousness, hence you skip the most unpleasant part.
Someone described this trick together with experiments on fainting years ago
Hey guys, I have a question about a CTB method that I hope someone could answer. I can get my hands on diflouroethane quite easily in the form of air duster. This rapidly replaces oxygen in the blood and causes unconsciousness. So the plan is as follows: book a hotel room with a tub. Fill the...
sanctioned-suicide.net
and was inactive on the forum since then.