Few days ago, I won on both 3DS & Wii U version of Smash Bros Online using Sheik (God knows how). I also love using Zero Suit Samus, Sonic, Mario, Bowser, & Palutena. No matter how low, mid or top tier is your character, everyone has the right to use their favorite character.
BTW, I'm not so good using Sheik. The ones that I'm really good at, is using Zero Suit Samus, & Bowser.
youre the only other sheik player i know of other than myself...
There a lot of Sheik Players. Maybe there playing Ultimate, or maybe there playing offline, or maybe there playing online, just you didn't find them yet. But trust me, there a lot of Sheik players out there... And very good ones as well. ;)