Perhaps our wording differs because of differing points of focus... Usage vs. accuracy of nomenclature. I agree that an unaltered natural minor scale is rarely used descending in jazz, and that jazz players and teachers discuss the use of the ascending melodic minor during descending passages. I'm one of those teachers. However, if we simply change the correct name and stipulate that melodic minor can now also refer to a scale that does not revert back to natural minor when descending, confusion ensues as is painfully evident in this thread.
Yes, jazz players tend to avoid playing a natural minor scale when descending, but truth be told they (at least the good ones) avoid playing an entire ascending melodic minor descending too... Or really ANY entire scale most of the time. We weave scale portions with passing tones to lead to chord tones or tension tones where our ears dictate. Typically, even if playing downard the ascending upper half of a melodic minor scale, we'll sometimes play both 6ths (raised and natural) and/or both 7ths (raised and natural) as passing tones so our intended destinations land on the part of the measure or chord progression our ear dictates.
I'm sorry, but melodic minor scales are different ascending and descending. I can accept the usage of "jazz melodic minor" to describe a scale that uses the ascending melodic minor in both directions, I guess, but it does a disservice to the many jazz players who do value clarity of terminology.
Can you give a good example of a jazz tune/solo that uses the melodic minor with descending natural minor tones?