When we were young my (now) wife kept jumping from job to job around the south east, and we'd move pretty much every year. As we were renting it didn't cost much to move - hire a van for a couple of days and job done.

However when we settled down with kids priorities changed, living close to a train station with good connections for work was less important, school catchment areas were, and the main importance is stability. The longest rental contract you can take in the UK is 3 years, after that who knows what will happen - maybe the owner will sell up, maybe they'll double the rent. A 5 year or even 10 year fixed mortgage gives certainty.

But the key thing is we wouldn't be able to rent if nobody owned properties they didn't live in.