I haven't been active in this community for months now, so things might have changed. However, when I was active, people were constantly complaining about a lot of stuff, and a lot of people had a mindset that completely ruined their fun.

The first thing I'd like to just get out of the way is that the myth that is the "1300 hole" or whatever you want to call it, is just that - a myth. The whole point of solo matchmaking is that you're supposed to tip the scales of the battle regardless of your team. You don't need to single-handedly win the game, you just need to play better than the average player in your bracket, and you will win more than you lose, and gain MMR. I'm like 1550MMR or something and I guarantee you that if you give me a 12-1400 MMR account I'll get it above 1500 in a day. Everyone at 1300 MMR is equally horrible at HoN, if you can't win more than you lose in that bracket you deserve to be there.

However, that doesn't matter. MMR is just a stupid arbitrary number that helps the game decide who to match you with, it doesn't matter in any other way. Games aren't any more fun at 1600 than they are at 1300, they're just harder. If you're not completely roflstomping 1300 games, you're going to get your a$$ handed to you above 1500 MMR and you're going to have a lot less fun.

I spent a lot of time trying my best to improve at this game, with my only goal being to raise this dumb arbitrary number we refer to as MMR. At one point I even got above 1700 MMR and guess what? Games were exactly the same, except it was much harder for me to dominate, in fact I was struggling in many games. As I got past my initial starting phase of only playing HoN and no other games, I started caring less and realized that I'm never going to be a professional HoN player. I never actually thought that I was going to be a professional gamer at all, and I didn't really ever have that as my goal, but if I'm not aiming to be the very best then why in the world should I care at all? What does it matter if you're 1300 MMR or 1800 MMR when you'll still always get your a$$ handed to you by thousands of players?

I think this is a major problem for many HoN players, they don't seem to realize that it's just a game. It doesn't matter if you win or lose, it doesn't matter what your MMR is. What matters is how you feel about the time you spend playing this game. Are you having fun, or are you letting other people ruin your fun without even trying, just because they're not playing up to your expectations? Back when I first started playing video games in the 90's, there was no competition. Playing video games had one single purpose - fun.
So if you're among the people who get angry when they lose or don't play well, or their teammates don't play well, take a deep breath and think about it. Do you really give a rat's a$$ about whether you win or lose this game? Of course you don't, it's just a stupid game. And if you're one of the people who think they're stuck in the 1300 brackets because of their teammates, seriously.. you're the one saying 1300 players suck too much and are dragging you down, yet you're also the one who sucks too much to beat them so what does that make you? A 1300 player. There's nothing wrong with that, everyone's been there at some point. Just accept it and focus on the game itself rather than the number you see when you aren't playing. It means nothing.

Another thing that can really ruin your fun is a teammate that's constantly nagging you. When people get angry about stuff I do, I usually just respond with "umad bro?" or some variation like "y u so mad bro?" or whatever other bad internet insult/joke I can think about, like your mom jokes or whatever. Anything that's completely unrelated to whatever he said to you.
This serves several purposes. First of all, you send the message that you really don't give a crap about what this insignificant prick thinks of you. After all he's just some kid, sitting at home on his computer and actually getting mad at you because you're not living up to his standards in a friggin video game. Who cares about this prick?
As a bonus you might also piss him off, which can be very entertaining. And if he gets annoying in any way, just type /ignore add playername and enjoy the silence.

This probably got a bit more messy than I intended when I started but well, I just felt it had to be said, so I said it. I hope someone else can benefit from reading this, and perhaps giving some thought to what they really want from this game. If you want to be a professional player then by all means, take it seriously. If you're not part of the 0,001% however, just loosen up and enjoy the game. It's just a game after all.