You’re talking about sociology, I was referencing anthropology at a more basic level - our shared humanity irrespective of colour, race or creed.
To be clear child brides are bad in my opinion.
However the simple words of “incompatible with civilisation” automatically implies an “us and them” division that strips away their humanity and assumes “we” are better.
If you want to discuss that then we need to look back at history. To take one example you’ve brought up - as recently as 800yrs ago the Christian faith said it was okay for girls of 12 and boys of 14 to marry.
Of course times have moved on and it’s no longer condoned. But as with fossil fuel usage and carbon emissions, it’s a privileged position to demand developing countries immediately abide by our rules when we’ve been walking that path of development for a longer time.