Well, because of how languages work and because people are idiots, they take one sentence and turn it into a dumbfest. Dude, people made Mario Party competitive. Rock, Paper, and Scissors have been taken to competitions. Anything can be made competitive like golf. Ooo, I went there.
I think Sakurai doesn't want to turn SSB into something like League of Legends, DOTA, etc. Street Fighter is competitive, but people still play it normally and for fun, but LoL has gotten so toxic over the years that playing for fun requires that you have friends so you can mess around with or risk getting banned because you're a noob, scrub, or cheater since people get so butthurt so easily.