To think, Teemo has slows with shrooms that he can use relatively safely most of the time, damage from those shrooms, not to mention it works amazing with Liandries Torment for tanks. He has a blind that stops all auto attacks, he can literally just pop out of nowhere to turn a potential 1v1 into a 2v1 shutting off the enemy auto attacks (which pretty much cuts adc's into nothing for as long as they are blinded)..... and has massive movement speed from his W passive, and then activate it for more to get you out of a fight if needed.
People have complained more about Bards being horrible or Nami in lower elo, or pretty much any squishy support. Bards for always ultiing horribly or trolling, or those squishy supports for not being "played correctly" either too aggressive or not aggressive enough.
You are really just upset by newbies or trolls playing Teemo. You can argue all you want but you have no basis of truth about how "useless" Teemo is. Play against a real Teemo and you will dread the day you played that game.
Enjoy your Teemo hating, but love him or hate him, you still think about him.