Bed frame legs don't touch floor
Centre rail feet are not supposed to touch the floor. If they do, they interfere with the flex of the slats. They’re only there to prevent the slats breaking when folks initially get into bed - or jump on the bed. Or... 

Generally, they should be a centimetre or so off the floor. 
Most centre rail breakages occur when people adjust the centre rail feet to TOUCH the floor. These legs don’t have much sideways strength and if they’re in contact with the floor (carpet especially) when the bed is moved sideways for cleaning, they drag on the floor and rip away from the centre rail. I’ve had to fix MANY of these things! 
(I install beds for a national bed maker).