I think there are a few differernt dynamics that go on. One factor though is that the hormones are massively more powerful in the case of women. Men don't always bond, especially with very small kids, in the same way mothers do. They bond with the mothers, and the baby is part of the package of that. By the time the kids are older it's less likely they will just completely bug out though it crertainly happens.
A lot of people are also kind of weak. It's hard to be the non-custodial parent where there is conflict with the other parent. Some dads just see the kids less and less and it becomes easier to just withdraw all together. I've seen the same dynamic with mums but less often, usually where the kids are in foster care but also in some cases where the dad was the main carer. So it may be that situation happens more with men because women are more likely to be the main guardian.
I also think there are some scenarios where there is a strong culture of women being the ones to decide to have the kids and being the main carers, and the men kind of slide from relationship to relationship. my dp grew up in a scenario like that, his mum had several kids with various men, there was no expectation that they had any say in having the kids or caring for them, and the fathers were only slightly involved. (His father had 10 kids with 10 differernt mums!) His belief even now is that the hierarchy of important family members are your mum, sisters, aunt, maternal grandmother, brothers, and then well down at the bottom of the list, father. None of that is formalised and there are some dads that stick around, but it does seem to be how many people in his community function. Personally I don't think it's a healthy dynamic, but there is a kind of logic to it I suppose.