[mod]

Having a detailed knowledge about how google handles permutations of email addresses does not fall within the realm of common sense, nor "basics."

The length of time that it has existed is irrelevant--it's simply not commonly used yet. It's advanced usage, not basic.

[PinguTS]

To be honest, I've abandoned that use for some years now and use simply a catch-all on my domains. Much easier to use, especially as many larger organizations rejecting the + because of "fake" email address.