Worked in the RE business as appraiser, realtor, and lender. Been around this block about 1500 times.
FSBO this could make a difference if there isn't commission set in stone on the selling side. Still, in this market, seller would be stupid to balk at a qualified offer to save 3%.
With a realtor, it's not "free" as the seller is baking realtor costs into their list price, but RARELY does a seller agree to sell a house for less because there isn't a realtor on the other side.
Because most houses transfer with use of a realtor, the entire market has realtor fees baked into prices if you want to look at it that way.
Not sure where you live, but realtors in most markets have their seller locked in at X% listing fee. They're not giving up half and putting it in anyone else's pocket if buyer-side has no representation.
If I'm the realtor, I show the seller my contract and tell them they're obligated to pay me X% of the sales price. If they're motivated to sell their house - which they should be in this market - they're going to pull the trigger. The only way I'm giving up half of my commission is to split the difference if it's truly the tipping point between making a deal or not.