That's not an example of people hiding information. That's an example of someone giving bad advice, because that person didn't understand how runes worked, or even read the in-game help for runes.
It would have been more polite to give you some good advice, but the fact is, a lot of heroes are pretty useless. The owners of this game deliberately make old heroes obsolete so that you'll want to spend money on new heroes. There's no way to rune Dragon Lady or Centaur to make them good.
That's true. You can't win with just one hero. You have to choose the right team for each fight. But that doesn't mean every hero is good. People on these forums will be happy to tell you which heroes are worth investing in. You don't have to (and shouldn't) level up all 80 heroes.
There's more than one strategy, so of course recommendations are different. But the guides do work. Alexei/Vamperus's guide does a great job of telling you which stats are the best for each hero. My guide tells you how to intelligently pick runes on your own. Between the two of them, you can learn to be good at runes.
Like any strategy game (runes being the only part of this game which requires any real strategy), doing it well is difficult. You can't win at Chess by shoving your pawns forward and hoping something goes right, or by buying the fanciest pieces. You have to practice, and learn how to do it right. You can spend $1,000 a month on this game and still lose every fight, if you don't know what you're doing. Or you can spend $0 and be one of the top players.
If you have trouble with runes, consult the guides. If the guides aren't working for you, post on the forums, with very specific examples. Things like, "I sent these five heroes against those five heroes, and my heroes have these runes." There are people here who will tell you exactly what you did right, what you did wrong, and how to do it better next time.