Nah. It is understandable that you see that Riot balances around competitive play because strong competitive picks normally get nerfed. However, what is strong in competitive play is often strong in Diamond and Platinum. If you didn't watch competitive play but instead watched high ELO streamers you would be forgiven for thinking that they balanced around Diamond.
Why is balancing for competitive play bad? Pro picks often filter down into regular play. When a champion is picked in competitive play there is always a play spike in normal and ranked games. When these champions lack meaningful counterplay (support Veigar) or lack interaction (Soloraka throughout the game) or are just consistently stronger than most picks at every point in the game (Sion) they become a problem in normal play.
Finally, people who say that Riot only balances around the LCS forget, for example, the Katarina nerfs and the Fiora nerfs, both before either was played in a competitive setting. There are many more examples than that. They don't.