I agree that it's not optional; in my book, a company mandating association with the degenerate cesspool that is LinkedIn as entry criteria for employment consideration is simply a non-starter, full stop.

If I disclose an email address that's directly traceable to my current employer---or even one provided to me by professional organizations I'm registered with---as adequate "social proof" (whatever that means) that I'm not "likely a bot/scammer", and a company's hiring manager is too blind to see the signal, then I'd write that off as a hidden trap passively dodged with confident relief.

Good for you, you'll be a principled unemployed.

Absolutely stupid advice for people who actually look for a job. You're participating in a social game, with well-defined signalling functions. If you'd like to actually have a positive outcome, you'll need to make use of the signalling functions commonly recognized, even if you don't like them.

(Plus, opting out of a commonly accepted path with the reason that you personally think other signals are as good and the other side is just too blind to see them sends a large amount of information about your ability to collaborate in larger teams)

You do you. There are jobs where you can get away with this, there are people with networks that allow them to play different games. But as advice to job seekers, it's actively detrimental.