why does nobody play lb

Because Annie just stuns her, since there is a cool down on your dash, and drops tibs and laughs.

Lb is to easy to counter

It's a good question actually. I haven't seen many LeBlancs lately either. She's certainly viable right now. She can kite juggernauts very well. If I had to take a guess it would have something to do with a) recent nerfs/buffs to make her less faceroll, b) Veigar's rise in popularity, and c) just forgotten about kind of like Caitlyn.