Floatingatoll said "It's not futile to reconsider conventions". This shows that's not a complete sentence, suggesting that you added a caveat or other clause.

Also, your preceding paragraph highlights another issue: what if the sentence being quoted has different punctuation than the sentence it's placed in? You wrote a sentence that should end in a question mark, but the quote should end with a period.

Good illustration, but also brings into scope the [sadly disappearing?] ethical requirement of not misleading with abbreviated or out-of-context quotations.

So, when a quoted sentence fragment terminates a sentence, the period should be outside?

> Blah blah "Quoted sentence in entirety."

versus

> Blah blah "Quoted sentence fragment".

Exactly, that's the rule in British style. In American style, the period goes inside in both cases.