Allan Shaw is basing his designs on measurements but with a subjective housecurve. And he is using old techniques, but tries to get the maximum out of it within it's limitations that he does not deny. And there is a public for this kind of speakers, that is larger than most here assume. His house curve is made to make speech sound natural, not true to the source. Those are not necesairly the same.
I don't think it's bad, because taste differ, and not everybody wants a superclean neutral speaker. Most want a speaker that is easy to listen to and is fairly close to neutral. And that is what his speakers do. If you are into that or not, is a subjective choice.
He is certainly not into real snakeoil stuff like special cables and so. Nor is he into heavy coloured sounds like tube amps and so. I more like those coloured amps, but i'm aware of it's limitations. Allan says his speakers should work with any amp, and a decent build cheap mainstream amp is often better than those esotheric audiophile amps. Idem with sources. And if people on his forums says it's otherwise he goes against it with real arguments, even if that may imply less sales. He is more on the ASR side than on the audiohile side of the spectrum, but he is not as fanatic and fundamentalistic on that as most here on the forum. And some of his public is into tube amps, even into SET amps (altough it think his speakers are not fit for that, to low sensivity and build for medium to low amplifier output impendance/high damping factor). In one of the discussions he mentioned that he mostly use a Yamaha A/S series amp for his personal setup, and those are fairly cheap and mainstream class AB integrated amps, nothing fancy or audiophile.
but Harbeth, AS, use the snake oil for marketing.
Remember e.g. the SHL5 40th Anniversary model „WBT connectors“ „special inner wiring“…