coffee addict: It depends who “they” were. If by “they” you mean Hungarian Jews (might be others too — don’t know) you are correct. If you mean Yekkes, Russians, Ukrainians, Litvaks Dutch (both ahskenaz and sfard) etc, then no. I think that starting shabbos after shkia in the US today would be lo sisgodedu.
While we’re on the subject, are there any sources behind the common practice to daven mincha after shkia and daven maariv before rabbeinu Tam zman?