When I was looking to buy a house, my agent received no financial compensation from me at any point. Their work was entirely subsidized by the buyer's agent fee - and we looked at a lot of houses trying to find the right one.
The negative effect of that is that they're incentivized to offload us asap.
Since Zillow and Redfin have existed for quite some time how, that service seems a lot less valuable. I'm sure it can be worth it in the right circumstances, though.
Suppose the market was hotter when you sold and your property was worth 2x the median. Is the same work worth $24k? What if you sold in a hot market in a hot neighborhood, which should make it somewhat easier to move the property? Does it make sense that this would increase the amount the agent gets paid?
For similar reasons, proportional pricing doesn't work well at the lower end of the market, where listings are often under $100k.
I had an agent get halfway through listing my house for sale and tell me his fee was 7%. Noped out of that one.