TL;DR TCW is propaganda making Mandos look weak, but RebelsRebels shows this was never true.
Remember, TCW was largely written like propaganda from the 'front, and heavily skewed toward Republic perspective. The Jedi are fearless, selfless heroes. The Clones are all fearless soldiers (Wewe see their humanity, of course, but it takes quite a few seasons before we see them as they were in the Traviss novels). The Mandalorians are an emasculated race, living like they deserve on a planet destroyed by their own lust for war.
RebelsRebels is written more from the perspective of Rebels, but much less like a propaganda piece. Mandalorians are fearsome warriors (Andand apparently have always been?) and this whole "Pacifist" craze we heard so much about in TCW has COMPLETELYcompletely evaporated in 5-10 years? I don't buy it.
I think TCW wanted to make the clones look special so they downplayed Mandos (Andand maybe Disney didn't want to play up the galaxy's favorite conquerors while getting kids to shell out $$$money) but RebelsRebels established that there were always Mandos as they were.
ALSO I refuse to acknowledge that Mandalore is a desert with its inhabitants living only in Cube cities. A CULTURE OF WARRIOR FARMERS LIVING ON A PLANET WHERE THEY CANNOT FARM, AND WERE ASSUMED TO STOP BEING WARRIORS is just ridiculous. I do not accept Disney canon in case you weren't sure. The Karen Traviss novels were by far my favorites and have been the single most influential Star Wars book series as far as my own writing and love for the series goes.