Because he seemed crazy easy. Possibly easier than Azathoth!

His cultists are super tough, but they spawn in out of the way places and only advance the doom when there's 6 at a reckoning. When you realize that there's only 8 reckonings the entire game....

Did we just read the rules wrong?

You probably played it right. At least there are no errors in what you wrote here.

There is already quite a number of reports that Abhoth is easy.

Me and my wife, we had cleared three of his mysteries in four turns.

We've played him twice, won once and lost once. If you're unlucky with Rumours etc. and doom runs out, things get very difficult. You do NOT want a board full of cultists when Abhoth awakens!! That said he is a little easier than the other GOOs, and I think that may be in answer to the sheer number of players who moan about the difficulty. Personally, I love that EH kicks my ass, but some players need to win games.

I love the Cultist encounter cards and wish (hope) that they expand the deck, and introduce these for more GOOs. Deep One encounter cards for Cthulhu etc.

I agree, Abhoth is certainly one of the easiest AO that I've played.

The statistics post seems to confirm it (see https://community.fantasyflightgames.com/topic/93953-eldritch-horror-statistics ).

I've played a game yesterday and finished with doom at 14, and mind that I took quite some turns to boost up my investigator's skills before tackling the mysteries.

The 3 mysteries I've faced weren't too hard either.