Some realtors provide a lot of value. Some provide very little.
I think it depends a lot on how much work you want them to do, vs DIY - and your own ability to do said DIY. Do you know how to figure a good market price? Can you deal with the legal docs?
It also depends a lot on how hard your house will be to sell. A good starter home is going to sell itself, but if you have something bigger or problematic, that can be different. Having someone set a strategy can be good.
The beef I have is the %-based commission. It's not 3x the level of effort to sell a $300k home vs a $100k home. It ought to be more of a fee-based system. I think over time, places like FSBO will chip away at the semi-monopoly service that realtors provide, and they will have to compete on cost more directly.
Example:
my home is currently for sale. I put a lot of effort and cost into making it ready, and used a realtor, because it has some funky things. She priced it a bit high (I thought), but it sold the first weekend for almost the full ask price. So that's great. BUT the commission was going to be over $20k!! For appx 4 hours of work on her part. That's insane.
Not related to her, but the buyer cancelled the following week (forfeited escrow cash even) because he had the school district wrong. So it's back on the market. Bummer. Sadly she is putting in some more hours...