It's not about what you do on the controller it's about what you make happen on the screen. Citing "pros" and their habits as evidence to back a claim doesn't mean anything. Personally i've found ways to play falco using X, I've never really seen anyone throw out three shines back to back (to back) and even if it is in one or two videos it's not practical to consistently do more than a double shine everytime you're pressuring someones shield. Hope this helps.
Edit: Also, I find it a lot easier to get multiple JC shines when I do use the claw in training mode, however, in a match, i'm too caught up in the pace of the battle to switch my finger style, sure with practice you could change that, but I don't think my shield pressure game suffers whatsoever from doing what my hands feel is natural.