I think you're wildly overestimating how useful that is compared to the complexity of the solution in the linked article. Mistyping a "," for a "." is as likely of a typo as typing "gnail" instead of "gmail". My personal email is over 20 characters long, and statistically nearly every typo I can make is something you simply can't check for.

To put another way, as anecdotal experience I've encountered many forms online that won't accept my email address or phone or whathaveyou because of buggy validation. I can't recall when I mistyped my email, but surely it's possible I've done it at some point, however the difference is in the price I pay. If I mistype my email and don't get a confirmation email or w/e I can always try signing up again. However if I can't use the form because the validation is bugged there is no straightforward recourse I can take as a user.