The fact that you are launched into a game where your fun depends on the performance of a bunch of strangers in a fast -paced, hostile environment that penalizes mistakes heavily with only short bursts of text to communicate is a recipe for vile players.
The weird thing is that the stakes are largely only whether the game will meet the player's expectations.
Also, humans are generous when judging their own abilities and are miserly when judging a stranger's abilities.
I don't find this genre fun whether I'm succeeding or not, for me it's 100% journey (casually and socially exploring the way mechanics combine into interesting gameplay - including failures as much as successes) and these games and their player base seem to be the precise opposite of that.
This game is massively popular in both of those regions.
I think MOBA games (except for the kiddie ones like LoL) are popular there because they like their games to be challenging. Most games today are rich in graphics but poor in gameplay, dumbed down for the masses to enjoy. At least in D2 and HoN even the most dedicated players still get a thrill out of sharpening their skills and being better then the other guy.
A lot of games involve team work, but it isn't crucial: that is you'll play better if you work as a team, but you don't need to and you can still enjoy the game if you ignore your team.
This is manifestly untrue for Dota. if you ignore your team you'll have a horrible time and so will the rest of your team.
As result this is actually an interesting social experiment: based on dota it looks like a lot of people don't like working as a team.
Imagine that baseball games were played using a non-discriminatory matchmaking service. So start of the "Dodgers vs Giants" game there would be a pause and then 25 "players" would materialize. Some of them would be athletes in their 20s with strong skills, some would be 40+ year old veterans who have good skills but aren't in shape, some would be 10 year old little leaguers who are very knowledgeable but inexperienced and out of shape, and some would be people who just randomly picked "play baseball" as their selected activity, not really knowing even what the rules of the game were. Then there is a "manager" who has to create a starting lineup, assign positions, and win the pennant.
Extremely frustrating.
Blizzard was working on "fixing" this by segregating selection of players into "twinks" and "non-twinks", "experienced" vs "non-experienced" and "hardcore" vs "casual" which helped but it still made for a crappy experience a lot of the time.
Also, I realized that I feel around ten times worse when losing than how good I feel when winning, so the expected derived pleasure from the game is really really negative, so I scaled my playing down a whole lot.
Because that's what the system was designed to do. If you're winning more than 50% it means that some percentage of the time, the game can't find 5 people who are better than you to put in a game. You'd have to compete at a semi-pro level to get this to happen.
Other games such as Dota 2, Starcraft 2 and League of Legends feature excellent match making. Anyone who takes these games seriously usually has a set group of people to play with, and only do public games when they have to.
I played HoN before matchmmaking, and it was quite interesting: you created a lobby, people would join, and you as leader could vet your teammates and kick the ones you didn't want to play with. Then the game proceeded once both sides were happy.
It took about ~10mins to get a game going, but the games were far higher quality.
The real hazard in DOTA / AOS / MOBA games are the people who slowly (or quickly) transform from quiet or reasonable people into insanely angry trash talking monsters. After all, the DOTA community got its reputation for being awful back in WC3, totally independent of any matchmaking.
There wasn't really a good way to tell who was going to be an asshole, and who wasn't going to be one.
You could be contributing to the problem a lot more than you think, e.g. by way of the Broken Windows theory[1].
I think it essentially comes from the nature of the game: as an individual, you're suddenly stuck with a bunch of other people you have to cooperate with. It's not like tf2 or CS. The teams are smaller and the stakes are much higher. People care about winning games in DotA a lot more than they do in most FPS games, where the journey is the destination. In DotA, the win is the destination and it's the validation of your abilities (k/d ratio doesn't cut it).
You would think having the win be so important would make it easier or better to work together, but the fact of the matter is most DotA players suck. Even people who consistently win public games still suck. Players hold everyone else to incredibly high standards and get frustrated when they feel like their team "drags them down." This is compounded by a feeling that, if you're doing badly yourself, you should scapegoat a team member in order to shift the blame.
DotA 2 is actually a lot better. I'm not sure why exactly, and it depends on your level. Maybe there's hope.