For what purpose do French speakers usually use "soit dit"?

Question

In conversation with my friend, I said jokingly:

Ce petit lit est bien moelleux, mais j’ai connu plus confortable, soit dit sans vouloir te froisser.

If you move the phrase "sans vouloir te froisser" to the beginning of the sentence, you don't need to use "soit dit":

Sans vouloir te froisser, j’ai connu plus confortable.

But when you add a phrase like "sans vouloir te froisser" as an afterthought, is it better to place "soit dit" in the sense of "d’ailleurs" or "soit dit entre parenthèses"?

I haven't given much thought to the exact function of "soit dit" until now, but I wonder how French speakers consider this phrasing in general? Would you use it to emphasise the afterthought aspect? Or for some other purpose?

Answer 1

Soit dit is a shortcut to cela soit dit and introducing here a clause that make the whole sentence close to an apophasis, i.e. you say something that you wouldn't have say in the first place. A literary equivalent of soit dit sans vouloir te froisser is sauf votre respect (with all due respect).

You can find soit dit in the similar idioms soit-dit en passant (by the way, incidentally) and soit dit entre nous (don't tell anyone).