Hmm, I can see how that sort of thing makes sense given the current state of the patent system, but personally I don't believe that so-called 'offensive' patents are irredeemable. Rather, it seems to me that they are simply far too broadly granted, and generally for far too long a time period. I have no problem with a patent-enforced monopoly if it is granted for a true innovation, and for a reasonable length of time.

For example, in the smartphone industry, where a product is old in a year and obsolete in three, it doesn't make sense to me for patents to last decades. On the other hand, it does seem reasonable to reward significant innovation by granting a patent for a long enough time period to establish a strong market position, before opening things up to competition. The tricky thing is, that ideal time period would be highly variable based on the industry and even the specific idea being patented. Still, surely there's room for improvement there.

How does the DPL benefit those who have no patents of their own? Copyleft is designed to benefit users above all else, even at the inconvenience of developers.