If people will actually pay for stuff (food, clothing, flights, whatever) through this agent or operator, I see no reason Amazon etc would continue to block them.
The most useful for me was: "here's a picture of a thing I need a new one of, find the best deal and order it for me. Check coupon websites to make sure any relevant discounts are applied."
To be honest, if Amazon continues to block "Agent Mode" and Walmart or another competitor allows it, I will be canceling Prime and moving to that competitor.