so basically you're saying that even using the loudness will introduce clipping and distortion

No.

I'm saying that any waveform in a digital signal processor that tries to go past 0db will clip, in digital form, before it reaches the output stage.

That doesn't mean that turning up the loudness will make it clip. Only if the audio source material has a low bass waveform that is very loud (close to 0db) and you have the volume turned all the way up to 0db and you have boosted the bass frequencies, only then will it clip.