I don't know, but Markus probably had good reasons for his suggestion.
No, Markus said only "Detect the monitor which is furthest away from the listening point and use it as the reference loudspeaker." That's all.
The only hard condition is: FL/FR have to be aligned as last pair.
Example is just my example. And for instance I have all monitors at the same distance. And anybody has usually FL/FR at the same distance. And fronts have KH750 in path with its delay so they look as the furthest.
But as I said problem is surrounds will appear after alignment much more near because of missing sub delay. Solution is to add this delay to surrounds in sw, Jriver in my case.
Maybe solution would be routing the same signal like front to surround splitting it and surrounds without sub.
FL+sub - (FR+sub)SL
FR+sub - (FL+sub)SR or FL+sub - (FR+sub)SR
FL+sub - FR+sub
This should be both frequency and time aligned.
Workaround of workaround.