I don't know the others' reasons. My primary reason was that I wanted a spool holder with ball bearings - because it had a very positive effect on my other printer.
I also wanted to free up the space next to the printer.
Then the question arose: where on the printer can the spool holder sit in order to disturb as little as possible and at the same time be stable mountable (without having to rebuild the printer itself).
And that's where the chosen position came in. However, this required a deflection of the filament by 180°.