That strawman is just about the same as saying, 'liberals seem to universally believe that nobody could be incompetent and every personal outcome is controlled by everyone else instead of personal decisions.'
It might be true that some people hold the belief but the belief is not true in "every measurable way". Otherwise you would never have stories of poor people becoming rich.
"Liberals seem to universally believe that the status you are born into will probably be the status you stay in your entire life."
The important distinction here is that competence isn't a factor and that the above statement is true in every measurable way.