> almost every professional recording you hear uses autotune
That seems a bit too general. If we narrowed that down to a few popular music genres I would probably subscribe to it. Plenty of solo artists wouldn't be caught dead using autotune or melodyne or whatever (outside of using it for effect/intentional distortion). When being an exceptional singer is your entire brand, you don't want to show up with training wheels.
> The video here is an extreme example of a very broad category of effects.
I mean, it's a joke, it's South Park. It's why I said 'jokes aside' in my next comment. However, if you're into jokes and such, I'd highly recommend that entire episode.
An alternative you've also heard extremely often is a singer recording the same line 100 times, then producers going through each word (or each syllable) to cherry-pick the sample where it was most on-pitch and blend them together.
Neither one of these represents the singer's real ability (whatever that even means), but both can be unnoticeable by 99.99% of the population when applied skillfully.