Pollux because your use case isn't that of everyone. Byobu never was meant to be just a private messaging extension. It was meant to have meaning to RPG forums as well for instance. They can use byobu to have temporary discussions limited to a subset of users where discussions do not simply get deleted.
Narrowing the functionality of an extension based on the opinion of the loudest users will often lead to disappointment with the rest. Extensions, in my opinion, should be flexible enough to appeal to the large majority not the vocal minority 😉
That's why I try to find the best way forward for everyone. One could make this an option for instance. Allow deletion by last recipient ...
