Fuck their silly mind games of calling political correctness.
But I don't agree that in past centuries, marriage to 9 year olds was a problem. Many cultures did this for practical reasons.
I think it's fair to say that it does not work anywhere in the world today, and any case of it's current practice is a bad thing.
May be you are right. 1000 years ago, a 12-year old boy marrying a 9-year old girl would have been normal (but still, what about a 53-year old marrying a 6-year old girl)? Anyway, right now there is no need for nine year olds to get married, as the life expectancy has risen by many times.
Life was short and brutal, the average life being 40 some, and many dying in childhood, or their teens. In many places, people were isolated in small villages, and only once every several years would a gathering of several villages be set up. That was pointedly a time to set marriage partners and this meant organizing it for the children.
Those villages had insufficient genetic diversity to create long term healthy populations.
I could go on but many factors combined to create circumstances favoring such marriages in times very different than today.
As for the 53 year old marrying the 6 year old, that reflects more on concepts of women as property than anything else. Remember, it wasn't just women that were property. When did English common law arise? When were the first concepts of people being their own masters? Etc, etc.