Is One Subwoofer Really Not Appropriate For 2-Chnl

I'm asking this question although I've read about this countless of times. I know 2-subs are preferable than 1 in 2-channel listening as they can load the room better for a more even bass response. However, is 1 sub really not appropriate and not recommended? Planning to go with a high-quality monitor + sub.

Anybody used a sub with Dynaudio Confidence C1, Focal Diablo Utopia or Totem The One?

Thanks in advance.