Yamaha's idea is to supply their receivers with what custom installation companies require: the ability to respond to one command for turning on and a different command for turning off. These are called discrete commands, meaning that they always and only do one thing: either On or Off. That said, there is also a command that will switch between the two; that is, if the Yamaha is on, this command will turn it off; if the Yamaha is off, this command will turn it on. This is called a toggle command as the state of the receiver toggles back and forth with that one command.
What I think edmund is saying is that Yamahas now respond to a toggle command for their current crop of receivers but that the particular command they respond to is not in the DirecTV remotes.
Do we call this Yamaha's fault for not using an older toggle command that is in the DirecTV remote, or DirecTV's fault for not including the latest commands in their remotes? It completely does not matter: regardless of the cause, it won't work.
Think about it, though: Blu-ray commands are not the same as DVD commands, but modern DirecTV remotes can control Blu-rays, while older ones could not. DirecTV added some new commands to their remotes to make this happen, so DirecTV responded to the existence of new commands. They did not do so with the newer Yamaha toggle command. (By the way, the toggle command is not actually on most Yamaha remotes, but it exists and remote control programmers know how to find it or derive it.)
Again, all that being said, DirecTV remotes have ON and OFF buttons at the top right. The remotes store discrete On and Off commands for most televisions. Why didn't DirecTV also include discrete commands for AV receivers? Answer: you and I cannot make things be different, so it doesn't matter why. They just didn't. The codes they include turn the Yamaha On, but not Off. That's how it is.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw