But, the real issue is that, as the system currently is, you need to have a license to list a property. Don't like it? You can do FSBO. But, basically nobody does, because the majority of buyers have a Realtor and are showing properties in the MLS.
Realtors should, ideally, provide value in the transaction. When I bought a house, for example, my agent provided tips on how to structure the offer that I'm confident allowed us to get the house we got. On the selling side, the should be providing marketing expertise, as well as negotiating the legal landmines. For example, if you were to list your own house and say "This room would make an ideal man-cave", you are opening yourself up to litigation under the Fair Housing laws (you cannot suggest who should live in your house).
Now, whether this is worth 5-8% of the sale price is another matter for discussion, but let's not forget that Realtors do provide some value.
(Not a Realtor, SysAdmin to an MLS)