Abused or not, the universally accepted current practice sets the definition. Annulments are seldom denied Catholics; if enough money is offered, and they go through the correct motions and make the right statements, there is seldom any denial. It's possible for a civil marriage to exist for years, with children being produced, and then the Church can declare the couple "never married," while the children are NOT declared illegitimate. Unbelievable hypocrisy.
Don't get me wrong. I'm not singling out Catholicism. Virtually every Christian denomination is guilty of this perversion of scriptural marriage. I'm only aware of a couple of congregations which take the marriage-related scriptural admonitions seriously. And, yes, they severely restrict the potential size of their congregations by doing so. But they have purity and power that mere size can't supply.
Depends on how you define “seldom.” They are denied. And the fact that you bring up the canard about not declaring children illegitimate shows that you simply don’t get it as far as annulments are concerned. What prohibits a “remarriage” is the existence of a sacramental marriage. Those who marry without knowing what they are doing are not held to the same standard as those who do. Those who had a sacramental marriage and abandoned it and “remarried” are not permitted to receive Communion. This is well known. Yes, some in such a situation ignore the rule (and some priests, scandalously, wink at it or worse) but far more often they leave the Catholic Church and become Episcopalians or whatever. Or they pursue an annulment. That alone shows that the Church’s discipline on this is stronger than most Protestant denominations.
The system has been abused. But Catholics have not thrown in the towel on divorce the way all the Protestants and even much of the Orthodox have. We’ve got huge problems, but we have not simply capitulated. Increasingly we stand out against the capitulation going on all around us.
I know it makes things smoother for you to lump everyone in together. But it’s just not true.