That's just the nature of the beast, from what I have seen.
I was frankly shocked that Arkham Horror got so many votes in that question -- there's no way in this lifetime or the next that my wife, any of her friends, or any of my friends' wives would play that game more than once, partly for the reason you've listed.
I have found that Arkham Horror plays the best when everyone knows the game equally well, or very close to equal. It's hard to measure, but everyone at a minimum should understand all the core rules, and there's probably going to be one or two people who have memorized the contents of each deck, and have read up on strategies for certain characters to help with decision-making.
For new players, I would do two things:
- Try to go over as many of the rules and concepts as possible before starting. I know that's a lot to ask, but if people don't understand the overall goal, the game can be extremely intimidating. Try to explain what's in each deck so people have an idea of where to go for things.
- Ask new players up front if they want to be coached and advised, or if they want to just feel things out for themselves. Some people take advise better than others, and some just want to learn by doing.
The first time I ever played, we played a six player game where only one of the guys had played with any regularity, so he acted as the GM for the session (managing the state of the game, reading the cards, moving monsters, enforcing rules, etc.). However, the rules weren't thoroughly explained beforehand, so we just stumbled around the first four or five turns trying to figure out what to do.
I would have loved to have been given advice instead of stupidly stumbling through a portal with no way of closing it after returning. The whole "what the heck are we even trying to do here?" feeling from just stumbling around left a bad impression on me about the game for a long time afterwards.
We ended up sending out a PDF copy of the rules to everyone to read as "homework" so we could be better prepared next time we played.