Some home owners who sell and rent back simply prefer the benefits of renting rather than owning a property and without having the stress of moving. And their monthly rent may be cheaper than the mortgage payment and if you decide to rent back, you are not responsible for any repairs to the property these problems would then be the owner's.
The advantages of selling and renting back are clear you get to stay in your own home, furthermore you usually get to keep your existing furniture and fittings. Your monthly rent will be assessed fairly and based on other comparable rentals in your aera. You don't have to deal with an estate agent or have to worry about your buyer changing their mind.
You will also have the option of buying Back your home at a later date once your financial situation has improved and settled. Buying back your own property is usually at a the going market price for the type of property and the area where it is situated.