Well, you don’t, but you’ll be missing something. There is a streaming equalizer in the app. It allows me to add bass and subtract treble, beyond what the fitter can apparently provide, and makes the streaming experience a lot better for me.
Also, there is a new equalizer that I haven’t seen discussed. I don’t know if it came with the firmware update I had or an app update. It just showed up! It allows for tuning bass and treble for non-streaming.
You need the app connected in order to have the benefit of these equalizers. I have Apple devices. I have no trouble getting reliable and automatic connection. I have two devices paired, phone and ipad. When I activate an audio source on either, the HAs automatically get the streaming sound. Nice.