How to understand the expression "it is not as if"?

[Cainntear]

Google "smart casual" to see the latest fashion disaster from the UK. I don't think it affects women, but for men you are supposed to wear suits 3 sizes too small, and not wear socks. And have 3 days growth of beard at all times.

I went to a wedding where that was the dress code. It confused the heck out of the American guests (some just showed up in slacks and button down shirts with no ties, because they understood the casual part but not the smart part).

I did my research and knew what it was, but couldn't bring myself to humiliate myself by dressing like a circus clown, so I went with what the Italians call 'sportivo.' I didn't match with the young people, but was happy to see the father of the bride went 'sportivo' also ...

That’s not what I understand the term to mean.

To me, smart casual is “no jeans, no trainers”, and my old manager used to define it as “nothing that would get you thrown out of a golf club”. In general I would go with polo shirt or cotton shirt without tie.

And as wearing no socks is likely to get you kicked out of a golf club, I’d be wearing socks (unless the event was at a boat club, as boaters often don’t wear socks).

[Speakeasy]

Casual dress ...

Five decades ago, I attended an exclusive college where a dress code was very strictly enforced; repeated violations of the dress code meant expulsion from the academy. In cases where a student was expelled for a "serious" reason, the college could and would refuse to transfer a transcript of the former student's grades to another institution. The former student simply ceased to exist; in fact, it was as if he never had! While I can no longer recall whether a dress code violation fell into this latter category, I can assure that the thought of not being able to transfer one's academic file was, indeed, sobering. "Casual dress" at the college referred to: a dark blue woolen blazer, grey woolen pants, a starched cotton shirt the collar of which was stiffened by a steel-wire mechanism of diabolic design, the school tie, black socks, and highly-polished, black, dress shoes.

Casual dress was required for anyone attending an outdoor picnic or a beach party. This was in the early-to-middle sixties and, at the time, everyone else in my age group was wearing cut-off jean-shorts, T-shirts and sandals, they were sporting long, rebellious hair, smoking illicit substances, expressing their outrage at all signs of parental/institutional authority and, generally speaking, having a lot more fun than I was. Invited by some friends, I attended one (my first and last) beach party in "casual dress" where, as could be expected, everyone else was "genuinely" appropriately addressed for the occasion ... it was not as if I felt out of place (sic)!

EDITED:
Tinkering.