I feel like this game is for different people and attracts people differently. When I got into LOL i was hesitant at first because it was advertised as the next big thing in gaming and of course because all of the characters and I'm a big Character lover (but on that later). MH promised me open enviroments, cute companions, a giant immersive world full of fantasy and wonder, weapons and armors in a huge crafting system to slay them beasts, nature versus population.
So playing LOL was like getting into Counterstrike. All the teamrage and the constant boasting about killstreaks and carrying a game, crit values and system abuse "Hey I got 64/2/0 last game again". That's simply not what MH stands for. If you win a fight in LOL it's because either someone in the enemy Team wasn't able to teamfight correctly or made a lot of mistakes or just simply disconnected. When everyone is good in both teams you win because your strategy was better. In MH you don't know the damage values exactly and If you win against a Monster you know it was your collective effort as a team. Sure someone might have that amazing endgame Weapon, sure he does most damage. You might boast about that last hit but in all seriousness, noone really cares who did the last hit, you're glad that thing went down for good and then it's carving time.
It's the whole feel of teamplay in itself. You're usually playing alone an that is where any other Hunter really shines: as a backup and company. "Drinking a pot and the Monster is charging at you? Let me just stagger that beast for you. Now get back to work on dat head, we need a knockout!" Or "He should be here any second, let's spam some emotes"
Another good point that I can think of is the similar feeling everyone has. You only have one character and that is yourself. Every Character is esentially the same. In other games, people might have different feelings and experiences depending on the characters they play and the enemies they have. Our only collective enemy that almost anyone can relate on is the desire sensor.
In LOL especially. I might be playing as Leona and personally hate any Zed. So I go chasing Zeds Midgame. I might be very effective in that regard but If I meet a Zed player, boasting about his achievements in silver 2 or whatever I might be rolling my eyes thinking to myself "well you obviously haven't played agains ME then." But if I tell him, he'll go on that I have no Idea of the feats he achieved and so on. Don't get me started on players whose favourite characters got nerfed lately.
I also play Touhou a lot. But that community is all about cute lolis and pictures of those. It's funny because we're all crazy and talk a lot of stupid stuff but the community in regards of connecting with others is almost nonexistent. Everyone longs for Gensokyo alone and for himself.