I don't know of anyone who believes people are static. You even say yourself in the next sentence "We all know that we all change". No one (at least that I'm aware of) goes into marriage expecting the person they marry to stay the same over time. Another HN poster (can't remember who) put it beautifully once: marriage is an agreement to learn to love the person that each of you become over time.
A marriage is a promise, a vow, to commit to this. Now, I could certainly see a situation where two people tell each other at the altar "I promise to love and support you always, well... unless we change too much". However, both people should be aware of these terms! You can't make an agreement that you will always, unconditionally support the other person, and then back out of it later because you changed your mind. If both people are in agreement that they might change and get divorced later before the marriage begins, then fine with me. It's not that different than dating with some legal benefits. But if one person thinks they're going into something permanent, and the other person has doubts about it, then that is really not fair to the first person, and I would argue it's essentially evil to be that dishonest to someone.
> further stigma to those who have gone through divorce
There is a stigma, but it's not on divorce; it's on someone who goes back on their word. What are my terms for divorce? If there is abuse or cheating. Those are my only conditions. And before I marry anyone, I will make it very clear that these are the only conditions in which I will abandon them, and if they don't like those terms they can marry someone else. The stigma associated with the vast majority of divorces is that one (or two) people were unable to keep a promise. I don't want to be associated with these kinds of people. My life is simpler and happier if I associate with people who will keep their word at any cost. Maybe your experience is different.