One significant problem with making your hardware dependent on an app is that if you are a washing machine company, you probably don't make mobile apps. So, you hire a contractor. They design an app without any expertise in the product or the domain, and program it on the cheap. It is trash. Later, the contractor goes out of business and you give the code to another contractor. They notice that the code is garbage, and not even garbage that somebody there made. Feature work is impossible, the app languishes. 1.5 stars in the app store. Every time there's an iOS update, people can't do their laundry for a couple weeks, until the one programmer working half time on the app can push an update. Later, you (the washing machine company) decide to sunset that product line, which means there's no updates to the app. iOS changes, the app stops working altogether, everybody has to buy a new washing machine.

I've been that contractor, which is why I will never be the owner of an appliance that requires an app to function.