As has been noted, walking begets walking and we're in a situation where everyone is trying to get the jump on someone else for that "hard to get week". As a result, more weeks become (or at least appear to be) "hard to get" as people walking make reservations for dates they never intend to stay (in an effort to start the walking process).
"Walking" exists in other timeshare systems (HGVC, for example) but I think there are a few things that have amplified its impact or visibility within
DVC:
1) Disney guests (and particular, those of us who frequent the DIS...but I would say even "generally" now) tend to be types that are very adept or keen to employ "trip hacking" to use whatever tools and tricks they can to maximize their Disney trip enjoyment. For most of us, gone are the days of planning a Disney trip a couple of months in advance, focusing solely on booking a hotel. Now many of us analyze in great detail attendance calendars,
points charts, dining reservation windows, virtual queue drops,
Genie+ strategies...etc to create the perfect (or best we can) trip. This approach lends itself to employing strategies like "walking" that might in the past never been thought of or considered.
2) DVC has created a highly complex division of seasons and views with the aim of best matching points requirements with relative demand. The greater the complexity, the greater room there is for analysis to find "sweet spots" where DVC hasn't got it exactly right and excess "value" exists.
3) Compounding the search for value mentioned in #2, is the fact that DVC is slow (or perhaps reticent) to adjust points requirements in line with actual observed demand. Theoretically the logic behind the complexity of DVC's division of seasons and views/locations is to even demand across the whole portfolio (such that we shouldn't see pronounced spikes in demand or difficult to book....). However, DVC also needs to market and sell a product and those places where there is excess value or sweet spots provide a nice story to sell buyers with less cash or less interest on how they can stretch their vacation dollars with DVC. This, along with the way the reallocation of points is referenced in the CCRs, has created some barriers to DVC reallocating points even where they might want to (referencing the 2020 points reallocation that created member outcry sufficient that DVC reversed course).