I see a lot of comments here along the lines of "I prefer to live alone because roommates are a pain in the ass", but I think there might be a lot of value to doing this because it's good for you. Living with other people forces us to corral our worst tendencies, to break out of virtual worlds to engage in the real one, to form bonds that will force us to grow and change.
I think it's strange that our preference in this area, but not many others, could be so dominant over what is good for us.
Basically: a team of researchers asked people if they'd be happier on their morning commute if they interacted with strangers or kept to themselves. Most said they'd be happier keeping to themselves. Then the researchers ran an experiment where a group were told to keep to themselves, a group was told to interact with a stranger for as long as possible, and a control group was supposed to do whatever came up. Those who were forced to interact with a stranger came away most happy, and those that kept to themselves were least happy.
We are social beings - it is how we have been able to survive as a species. And yet, given the choice, we often choose to isolate. I think people would be happier and healthier if we made more of an effort to combat that tendency.
I think a larger house like she's living in makes it a lot easier to mitigate "the bad room mate" problem mentioned in a lot of comments. They likely have some filtering and process to kick someone out if they turn out weird. And recruitment is hopefully easier if you have 4 other people looking for a 5th than posting an ad somewhere.
This does seem like a potential solution for the male loneliness epidemic. I think it would be harder to check out if you're around other people. Their house seems _very_ women-styled with cooking dance parties, twerking in the garden and the ingredients. But that's just one house, each house has their own style.
Before I met my partner I looked into communal living spaces, and if this doesn't work out I might do so again, and give it a shot. I don't think living on my own is good for me long term. I get too isolated.
I wanted to note that a lot of houses I've lived in have had couples. Two of our housemates in PR were a married couple who rented out the apartment they owned to come live with us. The husband was more extroverted than the wife and loved the company - and the wife loved that we kept him entertained and she got the room to herself more often :)
All this to say I simply think it's great to live with (good) roommates, whether you're male, female, single, coupled, or anything else.