It's a survey, so it relies on the surveyed to tell accurately the date they meet and how, so I won't be surprised that the line here is incorrect.
Or maybe they refer to using classified ads in the newspaper or over of those "romantic meeting agency" (I don't know the name in English, in French it is agence de rencontre) that existed back in the day
I'm curious if that included classified and dating messaging services. Aziz Ansari has a good book where he interviewed people who met using those services back in the day, and were embarrassed to tell people that's how they met.