My parents had to share a house with a couple when I was a small child. It was not ideal. Shared kitchen. Other shared spaces. Unless you are all on the same page about things, you are basically taking on extra parents. Other people telling you how to do such and such in raising your child which may be ideas that you're not on par with. When you have your own home, you can amicably disagree and go to the privacy of your own house. When you live with these folks, the disagreement may not be as amicable especially if they see that you're not implementing their ideas of what they think is best for your child.
Then there is the whole issue of cleanliness. What one person thinks is clean could be light years away from what you think is clean and tidy. This would cause untold levels of stress and discomfort on both ends. I'd rather have my own domain even if its only a travel trailer, than share living space with a bunch of people continuously giving their "advice" on what they think is best.