Pillar bedding puts the receiver's firm, hard contact points only where the pillars are. Pillar bedding came about when synthetic stocks first came out and their filler in the receiver area was too soft. Conventional epoxy bedding in these soft-core stocks didn't have any support like hardwood so metal pillars had to be put in around the stock screws. So, the synthetic stock makers finally got around to putting hard filler in the receiver area. Pillars were no longer needed, but most folks still though those metal pillars had to be used; they couldn't understand why they were no longer needed.
Equally accurate rifles have been and still are being built with hardwood and synthetic stocks using conventional bedding without pillars. Putting an eighth of an inch of epoxy between the receiver and the stock works very well indeed as that puts contact all over the recever where the epoxy touches. Regardless of bedding type, you still have to loosen then retorque the stock screws before shooting it if best accuracy is your objective.
But the rage seems to be pillars. If the receiver isn't pillar bedded, most folks don't beleive it can shoot accurately. And it doesn't matter what evidence they uncover to the contrary. Nowadays, the biggest advantage of pillar bedding is it benefits the person getting paid to do it. They do more work and use more material then charge more money.