Nope, you're wrong. I was pretty clear that those are two separate complaints. Paper is a form of DRM, and they specifically noted that as a primary reason why they were using it.

I would have (begrudgingly) paid for another electronic copy. However, had I known the first time that I'd just have to buy it again for a much-expanded 1.6 in a few months, I'd have waited and bought only the 1.6 version (assuming it wasn't paper only).

DRM is bad because it punishes your customers. I'm not giving up shelf space, ctrl-f ability, and loss of mobility because they chose this DRM.

And part of the reason that "upgrade discounts" aren't being considered is because it's impractical with a paper book. That makes sense, and is another reason not to use them exclusively. O'Reilly on the other hand, does provide upgrade discounts. This is always a better deal for both the vendor and the consumer, because the number of customers who buy every edition of a paper book they already have is incredibly small.