Half right, I'd say
It's true that many TVs (and other playback devices) are decidedly lacking in format support. But I do think it's still appropriate to blame DLNA for at least part of that.
Most of us here are technical, and understand all the complexities and interactions involved. But ordinary punters are not. And if DLNA is to mean anything useful, then it should surely be some guarantee of compatibility beyond just "yep, I can probably show you there's a server on your network."
The point of marks such as these, from the view of the novice consumer, is to make things simple and to make it easy to make purchasing decisions. DLNA ought to guarantee that when you buy a TV with the DLNA logo, and connect it to a network on which you have a DLNA server, you can access if not all, then certainly the vasty majority of your media.
You can lay the blame at the door of the TV makers, or the software, or wherever you like.
But ultimately, as far as the consumer is concerned, it is the fault of DLNA, which paints an image on its own website - just look at http://www.dlna.org/digital_living/possibilities/ - that is far removed from the reality experienced by many consumers.
If an organisation say "DLNA Certified® products are built to work together, even though they come from many different companies" and that turns out not to be the case, then I think it's pretty fair game to blame the organisation.