"By stating that Harbeth speakers work just fine with inexpensive amps, he removes an obstacle to the potential buyer, thus possibly making another sale."
Most successful speaker manufacturer's work hard to avoid creating obstacles for willing customers, not just Harbeth, I would guess.
Its probably a best practice in general for most companies so as not to limit their potential sales right out of the gate.
Since a lot of what people like or do not like is highly subjective to start with it does not make sense for a speaker manufacturer to make any stringent hard requirements regarding what you use their speakers with.
As long as the speakers are compatible and work with the gear and the gear is not likely to damage them, that's really all that is required at minimum.
But I would expect better vendors though would provide more detailed information that can help to optimize results technically for a customer if one asks specifically in help doing this.
Or if not, there is always your friendly audio sales consultant. They can provide more unbiased product options to the customer. The good ones will do whatever it takes to make sure their finicky customers get the best bang for the buck.
