I don't know from where it stems for the majority of opponents. For me, it stems from a complete lack of faith that the system would be well designed and even relatively free from corruption, and therefore that it would not make things much worse, while not actually solving the problem it's supposed to solve.

Certification exams already exist, and employers are free to require them to avoid the "crap candidates". Other problems, like security flaws affecting the users, can be better solved by imposing real penalties on companies.