Unless you are more important to them than some aspect of their own children? Yes. That has nothing to do with entitlement; you don't deserve anyone's friendship.

Children require a certain amount of time, and are given some degree more by any parent who enjoys parenting and/or has higher standards for parenting than what is required. If someone can't find any time for you because of their children, it isn't that their children have been deemed more important than you, it's that every single thing that they spent an hour a month doing with their children has been deemed more important than you.

I'm not being bitter here; my friends with kids found time for me when the kids were young, and now those kids are teenagers, so there's tons of time. It's just that all importance is, is priority. If you can't prioritize something enough to maintain it at all, it's because it's not important to you. Importance isn't some inner strength of feeling; that's a rationalization of being all talk and no action. If you don't feed something, it dies.