I think, given their friendship level, it's a platitude to avoid thoughts of being lonely and negative about being single, but rather see it as a positive experience to know who you are in your own right, make better decisions etc.
I guess in case you are like Julia Roberts character in Runaway Bride, whose favourite eggs and hobbies and interests were always the ones of the guy she was with etc etc until she found out for herself.
I think it's good for some people.
However, I have a friend who has never been single, people joke at him that he can't be...but he's a very strong minded guy, about what he likes, what he wants, his interests etc I just think he like being in relationships.
However, he's in same sex relationships with no kids or intention of marriage so he doesn't really have the worry of those responsibilities I guess.
I needed to take time out to find out who I was after marriage because I was damaged financially, emotionally taken for a ride, and had to think on future scenarios for my sons life.
I needed headspace to get around that, and what of me I'd lost, during that relationship. Another persons needs were not what I wanted.