This is just my $0.02, but if the trolls are anything like some of the rest of us, I have to assume it's because we're tired of the constant promotion of second-rate codecs that put ideology ahead of technical concerns.
Patent-free video codecs are the ultimate case of NIH syndrome. The major patent free video codecs (Theora, VP8, etc) are largely attempts to recreate/modify existing MPEG video codecs to get around the patents of the aforementioned original MPEG codec.The end results are codecs that aren't appreciably novel compared to the MPEG codec they're going up against, and at the same time it's not even clear (from a legal perspective) whether these codecs really are patent-free, or if they're infringing on the MPEG-LA's patents anyhow. Which is not an attempt to inject FUD into any of this, it's just that there haven't been sufficient legal challenges, and in the meantime it's questionable that these codecs can be so very similar to the MPEG codecs and somehow not fall under the associated patents.
At the same time the fact that these codecs are being pushed opposite the existing MPEG codecs only fractures the market and slows the adoption of new video technologies. We end up with Mozilla and Google flailing around with alternative codecs rather than buckling down and doing what's necessary to secure the rights to use the MPEG codecs in the first place, only finally doing the right thing after they've exhausted every other option. Web browsers should have fully supported H.264 years ago.
It's the codec equivalent of generic colas. Yeah, they're similar, but they're not the same and they're not what most of us are after. And in the meantime it quickly gets tiring of being told how we're doing it wrong by buying the more expensive product. There are certain things in life that are worth paying for, and a good/novel video codec is one of those things.
Which isn't to slag the patent free codec guys entirely. The video codecs have struggled, but the audio codecs have been outstanding. Opus is a roaring success, which I credit both to the development structure for the codec - involving many parties like the IETF early on while clearly shooting for novel/new audio codec - and the technical capabilities of the engineers who designed the codec.