This strikes me as another version of AutoByTel.com Remember them? They worked between you and the dealership, and generally got you a much better price on a car, usually the fleet rate.
They did well until dealerships figured out how to use the web, and then the company hasn't been anywhere near as relevant for a long time. It tough existing between web-based customers and physical dealers. There isn't a lot of loyalty, so as soon as tgere is a better price customers will change sites. Also, Autobytel's business is really offering highly qualified sales leads to dealerships. The basics are nothing fancier than that.
I see the same thing for Instacart. Grocery stores tend to be effective at shipping stuff around, but tge same "shoping" experience has worked for many, many years.
It seems like the grocery stores have a lot more power than Instacart, and Instacart is going to have a very hard time getting between customers and stores. It's going to be hard to make a profit when stores offer free/cheap delivery and develop their own shopping apps.