FINALLY I SUMMARIZE:
In Music "rules" (with punishment of deviations... ) don't exist.
In Music "STYLE" does exist! Rules, or better principles, are tools for identification and analysis of a Style.
NOBODY force you to Compose in a precise Style:
but if for some reason you want or need writing in a style, you MUST follow the rules and principles of the style.
(e.g. in a School Class, if you write a 4 voices Choral in the style of Bach, only exceptions used by Bach are accepted. You CAN'T create your own exception, or you are inventing your own 4 voices Choral style ).
WHEN YOU COMPOSE, NO RULES EXIST, BUT what you want and what you need.
Composing YOUR music, you MUST create your own Style!
(or you will be just a poor follower, even if it CAN be a rewarding activity, from a money commercial point of view )
I SAY. (full stop )