Consider a friend of mine who owns two houses. If he lives in one, the other will be "investment property" if he rents it a significant fraction of the year and thus banned. He can't move back and forth to avoid that because there are only 12 months in the year and it takes at least 8 months (per house) to satisfy the "twice as often" requirement.
The only way out is for him to leave the second house vacant the vast majority of the year. That pretty much defeats the purpose of owning a rental and it means that someone who'd want to rent is out of luck.