I seriously don't understand GAF's obsession with Earth Spirit. He is hard to play WELL and I almost never see him. But then again I just usually play All Pick. I've dabbled with him a few times and someone else on my team usually picks a support even after I pick ES because they don't know ES is support. Maybe he's more of a problem at higher levels of competition but in solo-queue all-pick you almost never encounter him and when you do it's nothing special.
It is all in what the hero itself is capable of. Here's only SOME of the things he can do by himself.
-Solo kill at level 3
-5 second multi man silence
-multi man stun for only 75 mana
-save teammates by pulling them out of trouble
-Easily put an enemy in a position to die
-have a 6 second damage over time that is refreshable and spreadable, and could technically get up to 36 seconds.
-escape on a 4 second cooldown
I didn't even mention everything. He is also effectively item independent and is not necessarily support, but really can do any role except hard carry. I find he generally goes best mid or offlane, but support is also a very viable option.
I would suggest watching Jerax's video of him on YouTube. It is from before the most recent nerf, but the concept is still the same and he is still overpowered. It sounds to me that at your level people just don't know how to play him.
Also for some reason it seems like everyone's initial reaction to ES is "I don't get it"/"This hero seems weak" then they watch someone that knows what they are doing play it and agree that he is broken as all hell.