Unless there is an overwhelming physical or sociological reason that only a particular sex can do a job then there should be no limitations on who that job is advertised to (not many women would be appreciated as men's restroom assistants, and vice versa, etc). Likewise there should be no restrictions on education, etc.
If it is sexism to only advertise to and accept men then it is as much so to do the same with women. What matters and the only thing that should matter is that the best capable and qualified person gets said job.
This goes not just for sex but for sexuality, race, religion, political views, etc. etc.