It is societies attitude toward women that is in question here. Most individual assistants were valued by those they were assisting. However many assistants would be even more valuable if they were doing something other than assisting, and so by having so many female assistants we devalued females who were able to do better work if allowed (they probably couldn't get the needed education, and glass ceilings were in play).
Of course in 1950 we didn't have computers able to do many of the things assistants did. As such we needed them to manually do various tasks that today computers do better. However the sexist making it females who are doing the job harmed the better female who could have done something better, and also the less capable males who couldn't do anything more complex anyway. (though there are a lot of jobs that those males could do that are even less complex)
Of course in 1950 we didn't have computers able to do many of the things assistants did. As such we needed them to manually do various tasks that today computers do better. However the sexist making it females who are doing the job harmed the better female who could have done something better, and also the less capable males who couldn't do anything more complex anyway. (though there are a lot of jobs that those males could do that are even less complex)