I would actually see it as a positive factor. Depends on the people involved of course.

Singles with kids are much better aware of each part needing separate time and having individual obligations, compared to someone who doesn't have kids, who might still be looking to merge into a twosomeness where their relationship is the center of the universe.

I do have kids and am not single, so I guess it's easier to see in hindsight. I guess it could be difficult for a single parent to find a single non-parent who is on the same page in maturity and responsibility.