I've seen plenty of zoolocks and played the deck myself quite a bit and you surely aren't always / very often in that perfect position. the thing is that you need to have a) both the Golem and the discard card in your current hand (and people run 4 discard cards at best) b) the perfect hand/curve so that you're left with a 100% chance to summon the Golem for free, if that chance is 50% or lower, the Golem might just be a dead card or an awful 3/3 for 3 mana c) all of this needs to happen early game otherwise a free 3/3 won't do too much, and again, if you discard the wrong card or don't draw the combo at all or whatever else could go wrong does go wrong, well, it's just a 3/3 sitting in your hand waiting for the combo or waiting to get played for 3 mana. which hurts the deck a lot. not to mention that you can't really replace any of the top tier 3 drops the deck is running.
very low odds of the card being any good is the reason why most people dismissed it. if zoolock gets more discard cards running in the deck (which I doubt), then the Golem will probably be played.
the Imp on the other hand is a much more consistent card, and it could see some play. I still said it wasn't good enough in decks with only 3-4 discard cards but I might have been wrong there, we'll see.