The payola charge used to crop up every time the small labels started to get hits. The big labels would shout that payola had to stop, then slowly they would go back to their old tricks. What good is it having a big company if some upstart can get just as many sales?
The industry has a lot of time and money invested in bands that may take several years to mature. They can't risk seeing their investment fall flat when the musical tastes move on to some new trend that kids heard on the internet.
Prior to the Internet, there was no way that artists could let large numbers of people sample their work for free (i.e. without either the artists or the people having to pay for it). Radio was great, for those lucky enough to get airplay; record companies could have captive artists by offering access to that rare and precious commodity.
With Internet undoing radio's monopoly, many artists no longer have a reason to sign with the major record labels.