What I see quite a bit, especially in this "seller's market", is 2 pronged - will I reduce my commission and/or why do I need an agent to sell my home...
My value proposition is strong because I know the market, I know to stay in my lane of expertise, I know the value of time and money - theirs and mine and my desire to serve is a driving force and a big part of my WHY - I am not the stick-a-sign-in-the-yard-and-forget-it agent.
There are instances, certainly, when I have reduced my commission, for strong and/or repeat clients, when a client is between a rock and a hard place or I have given some to help parties meet in the middle, but never if it is demanded.
As to why a seller should use a REALTOR, my team will tell you that I think everyone should stay in their lane. I wouldn't cut down a tree or rebuild your carburetor (things I have actually done when I was young, broke, and not a business owner) or pull your child's wisdom teeth. It saves everyone time, frustration, pain - and in the case of real estate, it could lead to legal problems. When I started in real estate, the purchase and sale agreement was 6 pages and now it is 8. Every single addition was made because someone got sued.
Before I knew the value I bring, honed my skill and treated my business like a business, I'd say that the commission charged was the 'industry standard' and I would have to check with my broker.