No, using regexes for this is terrible. I could write you a program that will parse html employing GOTOs, but it's been recognized as a bad programming practice. I'm not going to do your research for you, but this is not opinion, it's the result of people studying large code bases and defect rates within them. Same goes for overly long functions, bad variable naming, poor commenting, and so on.
A correctly written regex is not a bad programming practice. The insinuation that most programmers can't write or debug a regex correctly is disingeneous.
First, correctly written code can be bad practice. Regexes are a powerful tool, and have appropriate uses. I disagree this is one of those cases, but at -4 on my previous comment, I guess most don't agree. Second, I would bet the majority of programmers are mediocre with regular expresssions at best, and even worse at reading regexes written by other programmers contributing to code maintenance issues.
Finally, I may have been "incorrect" but "disingenuous" is an insult. I'll be charitable and assume you're using the word wrong.
Perhaps it's a difference of experience, but I really haven't met a professional programmer who doesn't understand regexes but still insists on using them for non-trivial tasks. Thus my usage of "disingenuous", because I have trouble believing that such people exist, and I felt you were trying to make a point insincerely, perhaps out of confirmation bias. I apologize if it came across as an insult -- it wasn't intended as one.
Using "regexex" for doing what is terrible? Using regexes for a lexer is quite common, and if you read his code, that's what he is doing, and then feeding the tokens to the parser.
