When using a power conditioner, why is it advised to run amps directly to the wall?

I demo'd many over the years through lending library at Cable Company, didn't find a single one that didn't limit current to some extent, this includes passive and active. This also compared to my own BPT 3.5 Signature witch has a massive Plitron LONO balanced transformer which also does same even when I run it on the amp/bypass circuit.

These comparisons mostly done with 845 SET amps which demand much current. To this day no PC for my 845 or 300B amps, I run my amps alongside 2 REL subs from a single dedicated 20 amp, 10AWG circuit, don't need or want PC here.

No doubt the power supply within amps is critical, first thing I look at with amps, only use monoblock amps at this point.  I want both to virtually equal what I see in stereo amps,  look at filtering and supply. Your amp should be quiet with this, I run tube SET with 103db sensitivity speakers, hardly hear any noise from power line.  Grounds important as well, I ran new grounding rod with equal length ground wires in order to not have grounds potential issue, no ground loops.