It’s a Twitter link so I can’t be bothered to actually read it. My immediate reaction is to ask if this is some form of bias.
Survivorship bias: People who had access to stable lives and institutions are more likely to have their photos passed down to the present day.
Selection bias: are you looking for old fashion photos or just statistically random old photos of people?
Sampling bias: Aren’t well dressed people more likely to be photographed because they are better subjects and because the privilege that allows them to be well dressed also affords them access to cameras and photographers?
Many of the pictures were somewhat posed... So people selecting to pose might have been in general those that were at the moment presentable. If you do not think you look at least decent you might not choose to have picture taken.
Survivorship bias: People who had access to stable lives and institutions are more likely to have their photos passed down to the present day.
Selection bias: are you looking for old fashion photos or just statistically random old photos of people?
Sampling bias: Aren’t well dressed people more likely to be photographed because they are better subjects and because the privilege that allows them to be well dressed also affords them access to cameras and photographers?