I think what popa is saying is that single people can help you avoid marriage.
I’m not entirely sure what I was saying. Part of it definitely is that what sounds neat and obvious isn’t always so.
On the topic at hand, I’m not as convinced as the OP.
Singles have a lot of opportunity to observe different couples, and see how they interact (like at shabbos meals). I recall once spending shabbos somewhere and knowing before kiddush that the couple did not like each other- which is probably why they had tons of guests.
Let me tell you, there were plenty of times I was single and eating somewhere and the hosts could have sure used my advice. Maybe I didn’t understand as well as I could have, and maybe I didn’t even understand as well as them. But in that moment, they should have been paying me.
Also, often not getting married is because you understand how relationships work and know the relationship is not working.