As I said, there are use cases where you are OK with a low-powered source - and there are ones where you aren't.

For example:

I have a hearing imbalance so I reduce the right channel by 6 dB (quadruples power requirements) and I would run this using oratory1990's EQ settings, which in turn decreases volume by 7 dB. So that is a reduction in max volume to 96 dB.

With music with limited dynamic range 96 dB peak loudness is fine. So when listening to most pop or rock the Apple dongle would still work. But I also like to listen to recordings of symphonies at a level comparable to that in a concert hall. This means that momentary peaks in the music can go up to ~115 dB (average listening volume is much lower). Clearly the Apple dongle cannot provide the power required for this.