Medium Wave and Long Wave bands are not "quaint". Those are the international designations for those particular wave bands.
Why can't they be both "quaint" and international designations?
The wikipedia description of a "preselector" sounds close to what they described:
A preselector typically is tuned to have a narrow bandwidth, centered on the receiver’s operating frequency. The preselector passes through the signal on the frequency it is tuned to unchanged, or only slightly diminished, but it reduces or removes off-frequency signals, cutting down or eliminating unwanted interference. However, a preselector does not remove interference on the same frequency that it and the receiver are both tuned to.
"Hams on various Internet message boards argue about the relative technical merits"...No they don't. This is not a specialised Ham Receiver. It was specifically designed for Short-Wave Listeners.
Are you sure they don't? Are you claiming that there's no overlap between hams and shortwave listeners? Here's one:
https://www.eham.net/reviews/detail/526
Several of the commenters have their ham call-sign as their userid. So if there's just one more message board where hams discuss the unit, this statement can be marked true.