Interesting parallel observation: when I worked for a regional newspaper some years ago, we rolled out products for the same demo as "mommy blog Twitter". We saw the same sort of isolated behavior - visitors to "mommy blog content" almost never strayed onto our mainstream products.
The same sorts of products delivered to "puppy and kitty" people didn't have the same effect, though the level of vitriol in the comments was similar.
Ditto. Launched (well, we built - client project) a social network for moms nearly a decade ago, and they were Not Interested in anything outside of the core offering - even recipes, which you would have thought would be interesting, weren't - until they rebranded along the lines of "recipes for moms", which changed that interaction overnight.
Some demographics choose tighter filter bubbles for themselves than others, and moms are likely up there, as the single most important thing to mothers tends to be being a mother - it becomes an all-encompassing identity for many.
The same sorts of products delivered to "puppy and kitty" people didn't have the same effect, though the level of vitriol in the comments was similar.