You can kind of get away with it, but even with just SMS you are losing a significant amount of flexibility that effects how much and what people are messaging you and is the exact reason why I stopped using a dumb phone. People sending pictures or emojis or to ask a question pointing to a link. People get tired of you asking what the hell they just sent you, whether it was a picture, or just a reaction with an emoji, because often both will fail to display right or at all.

True, and we considered that. But there are benefits to a smart phone that we also wanted them to have, just not all the time, and it should be easier to make a smart phone dumb than the other way around.