I'll admit, I am mystified at the thought of parents letting their adult sons live at home rent free, while doing their laundry for them, and so forth. My parents happily booted me and each of my siblings out the house as soon as we turned 18, sink or swim style. I'm thankful for it; I had to mature a lot to learn to survive on my own. Were I a woman seeking a husband, I wouldn't be looking for a guy who had never chosen a place to live, supported himself, had his own insurance, etc. The time to become an adult is before getting married, at least for a man.
I suppose with a very specific sort of parents it all might work out well, but I haven't encountered this sort of parent.
The day I turned 18 my mother was at the door with her hand out demanding room and board. Unlike my sister who lived at home rent-free till she was 27 and got all her school paid for.
I stayed with my mom for a while a few years ago after we put my father in a nursing home and I had left my road gig. I can't think of a worse scenario for a grown adult to be in. A lot had to do with my mom's control issues and her nosiness. Fortunately I was able to get back on my own but it was a rough couple of years.