The argument about that I’ve seen is that a lot of the brokers assume that they’ll have to do all the work for both sides of a transaction involving a FSBO or discount broker. I’d say that’s probably a fair assumption in many cases.
Of course, I’ve also heard comments from a few of them about avoiding listings with cut-rate brokers as a form of competition control, too.
A seller who really is savvy about pricing their home probably could do well by paying for a discount broker or an attorney to oversee the technicalities. A seller who is less than savvy would need more help.