I heard this argument and thought the same, but looking into it there is no standard definition for a recession. Two quarters is a nice layman version people share, but it does involve other factors. This isn't something that's changed recently, economic textbooks from the early 2000s say this too. Just something some people heard and ran with :)

When people hear these anecdotes, check yourself! In an era of fake news and bubbles you have to be accountable to yourself by researching if common sayings are really true before sharing them.