It's not about whether taking a year off work hurts career progression, it's about whether offering paid maternity leave creates pressure not to hire and promote women, regardless of whether they have kids. If the result was strictly "taking a year off work delays your career", that would be a fairly obvious outcome. Instead, what we see is "knowing some job candidates can take a year off work with pay discourages hiring and promoting those candidates".
It is, among other things, an indirect argument for paternity leave - if leave is symmetric, you can't preferentially hire/promote the people without access to it.
It's not about whether taking a year off work hurts career progression, it's about whether offering paid maternity leave creates pressure not to hire and promote women, regardless of whether they have kids. If the result was strictly "taking a year off work delays your career", that would be a fairly obvious outcome. Instead, what we see is "knowing some job candidates can take a year off work with pay discourages hiring and promoting those candidates".
It is, among other things, an indirect argument for paternity leave - if leave is symmetric, you can't preferentially hire/promote the people without access to it.