Why is surrogacy not allowed in Islam?

[Yahya]

Exactly, it sucks to find out you or your spouse can’t have kids but you can’t do much about it. Just make the best out of it and adopt a child and raise them as your own.

I'm not finding out. We're both getting tested before marriage. Can't be dealing with the drama of having to marry another wife, with the other one becoming jealous and bitter.