As I understand things DOTA2 is still in a beta state, by a company that actually knows what the means. They simply decided to charge access while the game is still under construction, probably to avoid the epic Valve wait time. Having looked at it when I bought the Christmas pack (haven't played it yet) just reading the stuff on it seemed to make it pretty clear that it wasn't a finished product.
THAT said, the reason why MOBAs are so inaccessible is because they are competitive games, where those who play them seriously are usually pursueing rankings and such. It's actually counter-productive for people to teach new players that they do not know personally and team with constantly how to play, because as much as you might weigh them down in a match where you join randomly, teaching your competition what to do is even worse, and if your not directly allied with them then you are their competition.
It's just like PVP in other games where people oftentimes keep a tight lid on their techniques, builds, etc... except in a MOBA there is nothing but PVP, you don't even have a PVE component to build from. The community reflects this.
To be brutally honest I'll also say that no tutorial is going to teach you how to PVP or play a video game competitively. Knowlege, and talent, are two entirely differant things, and there is no way your ever going to equalize someone who is inherantly good at this kind of game with someone who isn't. What's more no amount of theory is going to help you when it comes to actually dealing with other players, no bot can teach you, simply the way people move around is something a bot is never going to really be able to do the same way.
I'll also say something fairly contreversial here. Despite attempts to police competitive games, no company has yet to ever dedicate the manpower and resources needed to doing it right, this is one of the reasons why despite some high profile smackdowns in FPS, MOBA, and other kinds of games, the behavior continues and proliferates. Basically if you complain you get fed into a queue with tons of other people, and at the end of the day as long as they are making money the guys running the game don't care, the cheaters are paying customers too, so unless they actually get enough complaints to investigate and happen to actually catch the guy in the process (which might not be easy to recognize, depending on what they are doing) nothing happens, which of course ultimatly works to make the newbs on the receiving end of this even more frustrated, especially seeing as they are taken less seriously.
To put it bluntly, whether it's MMO PVP, a FPS, or an MOBA, chances are if you wind up getting constantly torn to bits by people you can't even see, or land a hit on if you can, the guys doing it ARE cheating or exploiting. The differance is that nobody takes you seriously as a new player, and you probably don't know enough about the game to really make a coherant complaint about what happened. After all there are ways to justify incredible kills happening legitimatly, but when they happen constantly... well, that's less likely.
In general I do not play games like this very often, but when I do the real "differance" usually occurs when you fall in with a group of people for a while, even if not an official alliance (it could just be a few hours with a random group that stays together one night), things slow down, and you get the abillity to look behind the curtain somewhat. Then it becomes easier to figure out who is cheating, and actually to avoid them, because even if you still suck it becomes possible to tell what a given character/spec/weapon should be able to do.
You also, on top of everything else, and aside from the cheating, need to understand that every new player needs to be willing to put in their "victim time" unless you come in with an established alliance of some sort. In general the longer the game has been around, the longer you should expect this to go on... we're talking months here, not days. Simply put wen veteran players who are good are still learning new things and adapting to change (and improving) you as a newb are not going to suddenly just play a few weeks and then bump past a magical curve and become good at the game (this can happen with very talented players, but not for the average player). In general this tends to mean that the more established a game becomes, the less approachable it is.
That said if you stick with it long enough eventually you'll develop the same kind of elitist mentality even if you kind of suck. To put it bluntly, the biggest contribution to ranked PVP by newbs is giving the veterans someone to grind to "repair" their Kill/Death ratio after a bad streak against other veteran players. You'll actually be fairly grateful for it when you get to a certain point, and even find it amusing when you know you suck overall but to hear newbies talk about you like your the god of death or whatever.