Be a better league player

So, basically, what I wanted, I saw some yt-ers and streamers who are high diamond or even master and they keep changing their in-game profiles all the time, another day I was reading something and same thing came up and it was about that I shouldn't only play games on my main account and I should have at least one or more accounts. Can someone from high elo explain me why should I play like that and what effect would it have on my ranking up out of silver and by some accounts skyrocket me to at least high platinum. Second thing I wanted to ask is, I am support main and I love to play it, but till now I wasn't so competitive and I want to learn and climb in season 8 as high as I possibly can, so what support champions would you recommend me not to just climb out of "elo hell" but champions to master. And last thing which is connected to my first point about multiple accounts, I've heard that you shouldn't play all the time and I would need to organize when I should play ranked and when I shouldn't. Thanks to anybody who will help me and good luck in climbing.