We are made to think there is no DEC in print. But as long as you keep printing unlimited vouchers and give it a utility which in return can produce DEC in some way, DEC is going nowhere but sink. For example, They let users buy DECB with vouchers (which has an infinite supply as already mentioned) and now they are happy that we are burning so much DEC, which is not if you look under the hood. A good amount of those DECBs came from vouchers. So, yeah we printed again.
Any voucher discount given on any product which can be bought with DEC also works in the same way.

And the good thing is I am not the only one thinking this way

They should stop coming with new tokens(grains, time crystal) and give the existing token utility.

People still earn DEC from selling cards, rental income

We should not be worried about this because it isn't getting printed, someone is buying to pay for them.