Discount cupboard remains uncharacteristically bare. Is this because?…
a) WDW doesn’t currently need them to fill rooms
b) inventory low from continued closure/staffing issues
c) hubris
d) discounts just around the corner
e) a and b
f) other
I'll play

I think it's a combination of a, b and f.
I'll start with
f) other: weaning people off discounts as part of strategy:
Those of us who enthusiastically follow WDW discounts had noticed that over the past few years, discounts had gotten more selective. Meaning, that even if there was a discount advertised for the period, some nights (weekends/holidays) were full price. And you would only know that you were paying full price, if you clicked on the individual nights' rates, otherwise it showed that you had the promo applied, so you may incorrectly think that you had gotten a discount on your 7 night stay, when the discount only applied to 4 of those nights. Discounts were available selectively, only for specific dates, resorts and rooms that they were having difficulty filling. For example, Poly was often quietly excluded, meaning a discounted room would not show, even when there was available full price, while the CBR Pirate Rooms were discounted in abundance.
Add to this that as part of their long-term strategy of "weaning people off discounts" that they had to offer after 9-11. They've been trying to wean people since 2010; that is a decade of trying to wean people off discounts. They've been slowly eroding a bit at the discounts because suddenly not offering any "special offers" would be too drastic. It is considered a good strategy for higher-end products to limit the offers in order to maintain the appeal of the product.
Now, I don't think "F" accounts for everything we are seeing. I don't think the hotel inventory is fully back due to labor shortages. Which means they may not have as many of the rooms that they would normally have difficulty filling. The question is, once labor shortages are a thing of the past, will they continue matching the staffing to the demand, for higher profitability?
And this is where "A: WDW doesn’t currently need them to fill rooms" comes in. There are many guests that this is a one-time special vacation and they are not going to care if they have a discount or not. And many guests have gotten used to booking and assuming the discount will follow. I would love to see their projections on number of rooms kept at full price vs cancelled because of no discount (and the comparison against a higher number of discounted rooms). It's probable that it's worth it for them to lose some bookings for the sake of keeping more at full price.
I do think we'll see discounts pop-up ("D - Discounts will continue"), but they will continue the trend that we've been seeing: only very specific dates, resorts and rooms that are not going to sell well.
In the past, I planned trips when I saw a good discount, which explains why I have not been to WDW since July 2020. I'm always watching closely for new discounts.