All things being equal ( sort of ), when all you have is the minimum qualification for the job ( e.g. fATPL ) then you'll need 'something else' to make you a more interesting recruitment prospect, e.g. that you A'Levels, or that you've walked to the North Pole, or that you've been a stock-brocker responsible for billions of £$€'s, i.e something / anything to give you the edge over the other applicants who also have fATPL's.
Also, and imho, when all you have is a fATPL it really makes no difference if you have 251.3 hours, or 280.5, or 600.1 hours in light aircraft - where it's more about what you did to get the hours, i.e. their 'quality' rather than their quantity - as the airline people will see you much as just another person with a fATPL.
Let's maybe put it another way....
The airlines know what they can provide for you, i.e. a job, a type rating, training, opportunity........ but what do you bring to the airline ?!