why cant i ever get the position i put as my main in ranked?

unless its support which i main since i started league 3 years ago cause it always seemed to be the least desired role and i wanted to help my team by doing that, i cant ever seem to even close to reliably get jungle when i try and put it as my main... also why cant riot make supports more fun to play with giving them the ability to carry games as a normal thing? in other words having aggro supports be more accepted. I know in high elo champs like braum, janna, thresh etc are super important for there cc I feel in low elo a great portion of the time my support abilities arnt being taken advantage of nearly enough by my teammates to make it fun if not tilting and of course i have to rely on other teammates to ultimately win fights cause they are the ones who deal damage

I feel if champs like brand, lux, lulu, sion, volibear were more accepted as mainstream support champs support would be a way more exciting position to play.