Not any worse than Dan Grissom with Jimmie Lunceford.  And I don't think it is so much a matter of being a "purist". Even tearjerkers can be swung (in a way). But I guess they were part of the repertoire (dictated by popular tastes back then) of the big bands (Black ones included) that they did play at live dates but that otherwise never got recorded (waltzes, etc.).

I will watch it soon!

I agree, this has very often been the case, and the rule rather than the exception. There are countless reissues that reproduced the facsimiles of the front and back covers of the originals but often have a few lines with personnel and recording dates added somewhere (wherever there remained some free space) in the original layout of the back cover. And I do not even count the number of original (or very early rpressing) LPs where I've added the recording dates in pencil (so erasable ) on the back cover somewhere near the lineups.  As for "new jazz", I cannot really comment because there is not much brand new jazz releases I am buying. But overall, among those I did buy (most often CDs) I'd say it's about 50% with and without recording dates. But indeed the recording studio always seems to be mentioned (and the recording dates - if indicated - buried somewhere nearby), as well as the lists of thanks to a milion people out there. 

December 10 Franco Ambrosetti - 1941

In two consecutive days, we've lost two of the most important Spanish rock musicians, two icons, two excelent musicians, vocalists and composers, as well as probably our best representatives of "sex, drugs and rock'n'roll".  May you rest in peace, motherfuckers!   Jorge Martínez (70) from Ilegales   Robe Iniesta (63) from Extremoduro