Do driveway sealers do anything?

I wondering if driveway sealers (for asphalt) actually do anything more than make it black and a bit slippery?

I’ve always assumed they were good for the driveway, but now I'm wondering. We got chatting about it at work the other day because a couple of us are getting new driveways, mine’s coming with the new house. It occurred to me that the driveway at my old house had never been sealed in 30 years as far as I could tell, but the neighbors on both sides said they had sealed there driveways every few years since they were new (a development so all 3 were exactly the same). Last summer, one of the neighbors replaced his driveway while the other had his resurfaced, but mine was still fine and clearly in better condition than either of theirs.

It also occurred to me that of the 3 states I’ve lived in, I’ve never seen sealer put on a road. I would think that if it actually helped, the state would seal the roads as standard maintenance. All 3 states did tar cracks every spring and all three states also would tar and stone at least once before repaving, so I’ve got to believe that helps. But they never sealed the roads.

Just thinking about it, I would think keeping the driveway black with sealers instead of letting it fade to grey would mean that it gets much hotter in the summer which can't be good for it.

Any thoughts or better yet facts?

 

What exactly did it do?