That is true, but there are also conditions where low-powered studies degrade meta-analyses. For example, if the panel attrition is caused by self-selection on

That is true, but there are also conditions where low-powered studies degrade meta-analyses. For example, if the panel attrition is caused by self-selection on unobserved variables, then the study contains bias that is not (and cannot be) accounted for, which skews the meta analysis. But yeah, those concerns are mostly about measurement not sample size.