For many software patents, I'd agree with you.
The problem with video compression is that many of the patents involved do represent real research, the expensive kind. They aren't one-click shopping patents. They're fundamentally pushing forward the state of the art. The people who do that work are expensive and need a lot of time, so, there has to be some way to pay for their efforts. Google's approach of subsidising all research via search ads is perhaps not as robust as one might hope for, even though it's convenient at the moment.
I don't know if DASH specifically is complex enough to deserve patent protection, but if you look at the massive efforts that go into the development of codecs like h.264, h.265 etc, the picture gets more complex. It's not pharmaceutical level research budgets but it's probably the closest the software world gets.