Do you mean that you can't write a tune that it structured as 4 3 bar phrases and call it blues?? Sounds like a very austere remark. I know I have heard blues rhythm played as 4 3 bar phrases. I have one playing in my head now, I don't know who it is but it's definitely a 4 3 bar form. And it's blues. I wouldn't call it anything else.

I know certain music follows a traditional form, but like you added Jazz. There are certain rhythm patterns that you would call a "jazz rhythm", but when you listen to several different songs. Not all of them follow the same rhythm patterns. There's always some sort of re-invention or new outlook on things. So when this does happen would you then ceize to call the music jazz???