My wife and I weren't able to get financing to get into a unit we liked because the building had too high a percentage of rentals. We are now in a small 6 unit condo building and there is a rule that only 1 unit can be for rent at any given time. However, it is also possible to apply for a financial hardship exemption to rent out your unit if there is already another unit for rent. So if one or both of us lost our job, we could rent the place out. This seems like a nice compromise. Currently, all unit are owner occupied.
Eventually, my wife and I would like to purchase a live in rental property, but we aren't sure what we would want to do with our condo. If we rented it out now, it would probably get right around the monthly mortgage payment price. So, we could continue to build that equity for the cost of being a landlord, or we could sell the place and use the cash that we would get to put down a bigger downpayment on a multi unit property. We are about 5 years out from having to make those decisions, but the rule actually probably helps out when we go to sell, because there will be more potential buyers. I definitely think that easier financing is more important to widening the pool of buyers, than the ability to rent the unit out no matter what.