His "explanation" is kind of vague, at least to me..
Indeed, very vague to me too. IMO, the author wanted to create the impression that the design of passive loudspeaker X'over networks, which sorta makes or breaks the sonics of a loudspeaker system, is something like rocket science, which greenhorns should not touch.
Back to your question, my straight forward answer is LESSer order
of filter BETTER will be the sound
. 1st-order filter (6 dB/octave down slope) will allow music signals to pass thru with minimum amplitude attenuation & least phase distortion. It is the phase distortion that screws up the music. Why? Less order fitlers needs less parts. Less reactive parts (capacitors & inductors) in the signal path therefore delay less on the music, thus better the music will sound. It is the most simple X-over design using least components, & is therefore cheaper to build.
But, 1st order passive X-over network is not all angel. It depends a big deal on the 'muscle' of the tweeter chosen as there will be larger overlapping of LF energy 'leaking' into the HF band which may damage the tweeter's fine voice cois. There's why we can see series resistor is often added upstream of a tweeter as current limiter.
Also it is least amplifier power efficient vs other orders (2nd-order=12dB/octave, 3rd-order=18dB/octave etc etc) as the larger overlapping LF/HF areas means more electrical power from the driving amplifier dissipated uselessly.
Also, always position loudspeaker with 1st-order fitler facing ON-axis
to the listeners to minimize off-axis acoustic frequency response variation, the common weakness of lower orders of filters.
So my first choice of X-ver networks will be 1st order fitler which sounds best to my picky ears given the above consideration.
That done, the 2nd step is to make a passive X-over network more efficient & sound even better all around. (somewhat O.T.)
This is to modify the X-over network (be it 1st order or 4th order) to multi-pair-wiring instead of its common single-pair wiring. My years hands-on experience has proven
such modification works bigtime.
It improves the driving amp efficiency, raise the X-over power handling capacity & overall sound quality of the loudspeaker.
Hopefully I've pin-pointed the key knowledge one should know about X-over network design. Save studying those rocket-science-like loudspeaker "cookbooks".