IMO it depends on how you look at it. In addition to the 4 formal reallocations (OKW mid 90's, 2 yrs of across the board reallocation a few yrs ago and the THV), there have been other items you might look at as such. Just the points changes from OKW to BWV and beyond were effectively a reallocation and increase, AKV and BLT? both had view rearrangements. I believe the S-F stay was a predictable casualty though I do believe that without some type of minimum stay requirement, they went overboard with benefits to those that stay weekends.
As noted, they do but the decreases have never been as large or obvious as the increases. And while there are limits on how much things can change in a year, those protections do not appear to extend to the lockoff costs and as DVC has proven, all you have to do is make changes over 2 years anyway.
Actually DVC has an obligation to change the points costs if the demand gets too far out of balance.