Mental stimulation wouldn't be the issue. Risk of violence or disease, however...
Most of them are choosing one (purportedly, although I think I'm right that neither of us has tried it) brain-dead lifestyle over another one.
That's why I get irked when people talk about housewives becoming "braindead" from being outside of the economy. What makes the typical mind-numbing office life superior to a (supposedly) mind-numbing domestic existence?
Every housewife I know has some kind of mentally stimulating hobby, and most of them make some amount of income from it (photography, crafts etc...). In fact most of them shouldn't really be called "housewives" any more than male remote programmers should be called "househusbands".
Obviously children are not in control of who takes care of them, but that would be true whether the parents worked or not; parents decide how their children will be cared for in any case. Also, I'm not sure if you've ever tried to browse reddit and watch a toddler at the same time, but I can say from experience it's not as easy as you might imagine. Children, especially when they are younger than school-age, demand a lot of attention just to keep them safe and healthy let alone educated and civilized.