Is it weird people use this reason to justify why age gap is wrong?

I see some people say age gaps are wrong because the older person, usually a man is much stronger than a young woman eg 20.

This makes no sense because the man will nearly always be stronger than a woman regardless of age, yet people don't say it to hate on couples of same ages or close ages.

Is it weird people use this reason to justify why age gap is wrong?
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