graffiti is about more than just a medium. u can use spray paint to paint anything but just the act of using that paint doesnt make it graffiti.
you can paint a mural using spraypaint but its not graffiti. even if ur a graffiti artist but u decided just to paint a mural its still a mural. graffiti is about letters. all of this has already been said im pretty sure.
and as was said before if your letters dont flow then its going to be astheticly wrong isnt it. toys arnt being taught a super specific style just the most basic elements of letter construction.
thats no different to being in art class. your still being taught by people who are more advanced than u. what you do when u finish art school is your choice, you can throw out whatever concepts u hated but it will still form the basis of your artwork. if u have no lettr structure then its just going to look like shit