Why isn't Razor picked more?

I've been watching JoinDotA, Dendi and Synderen's stream for several months now, but I've never seen the guy.
I recently got access to the game thanks to someone sharing a key with me.

In matchmade games he's still never seen. In bot games, however, I see him almost every game (on the enemy side). And every time he's a pain to deal with (do note, I'm nowhere near a decent player).
He can drain a whole lot of damage from your carry, has AoE magic damage and his Ultimate will snipe out any low HP targets in addition to reducing the target's armor. When targeting him with any targeted spells you'll take damage in addition to getting purged and slowed.

His kit just seems amazing to me and every teamfight Razor bot manages to rip people a new one.