Nah, your “arguments” are just shit as usual.
Guest characters help bring new players in (like myself back when Link was in II), and those players will find more characters to like in the roster or find new ones in the next game. Nothing about guest characters keeps it from achieving greatness, guests just help bring in new players as the rest of the roster grows. Guest characters have always helped Soul Calibur.
But if we go by your logic I guess Injustice 2 is the most trash fighting game ever made for destroying its integrity and player retention and wasting tons of resources pandering to idiot fanboys