At least in the US/North American markets Dolby is mandated (i.e. has a monopoly) as the broadcast standard for ATSC audio. While cable companies could do something different re-encoding feeds/content, that is a step they would want to avoid. Cell phones is are a bit different, there you only need the Dolby decoder because some of the content stands a reasonable chance of having the audio in a Dolby format. But the manufacturers are sort of forced to include it because customers expect to be able to watch anything they want. Many streaming systems also use Dolby encoding for some of their content.
This is independent of what your playback system is, i.e. 5.1 or simple earbuds - you still need to decode the audio. By blocking post processing options from other suppliers Dolby is locking everyone in to "their way" only. I am not knocking Dolby's work, they have some very smart audio people and do significant R&D. It's the heavy handed attempt to monetize that work that is the problem. When used for something like ATSC (use of a publicly owned commons - airwaves) companies that have their technology selected are supposed to license it under "Fair and reasonable terms". Blocking new and innovative methods of post decode sound field processing is neither fair nor reasonable. The companies that work in this area are typically small and can't afford the lawyers to take on a giant like Dolby, so they will (and have) given up.
Are those third party efforts better than Dolby's? Perhaps sometimes yes, sometimes no. The concern with this new position from Dolby is that you and I will never get the chance to know if someone has a better product.
Dolby is also a patent machine and ties up their technology for long periods of time by playing the system. It's a pretty clear case that at least for technology standards that use a public resource (airwaves) should use "open source/non-patented" technology to avoid exactly they type of issue being created by Dolby in telling audio system designers what they can and can not do, and limiting the options for customers.
In some other parts of the world Fruanhofer's MPEG-H is being used for broadcast of audio (for TV), I do not know what restrictions they might place on customers as it's fairly new.