Firstly let me state I CANNOT PLAY POS2 and am a average POS4 at best.
(I am only 4.2K mmr so I realize I am low mmr you don't have to tell me)
So I only que pos1 pos3 pos5
But the NUMBER one problem in dota is POS4 players.
They are the actual worst lowest skill players. They don't want to play support bt can't fast que for core roles so they search pos4
Every single POS4 player thinks they a mid or pos1
Will always go carry items. Will never place a single ward or sentry. When asked will always say thats POS5 job.
Will be in lane for approximately 1-2min max then "roam" meaning afk jungle or kinda just hang around mid/safelane sapping xp.
The most built items on pos4 will be dagon ags. This is WITHOUT exception. When asked they will say its pos3 job to buy meks/pipe/lotus/solar
Most common POS4 heros are Mirana(aka miss first arrow leave lane) NP die once afk junle/Rubick kinda sap xp never block camp or pull or contest pulls and techies suicide and feed like twice then go plant mines in jungle for rest of game never doing anything.
Every position has flaws
But pos1 usually afk farm all game and hope to go late
Pos2 usually farms and never ganks bt tries to get items and carry game
Pos3 solo lanes tries best to get xp and contest, always intaites fights and usually feeds due to afk pos4
Pos5 tries and wards usually gets like a glimmer/then blink ags. But mostly tries to do their job
POS4 IS BY FAR THE LOWEST SKILL PLAYER BASE IN DOTA 2 ATM
It would literally just be better if they put in a permanent junlgle role like LEAGUE OF LEGENDS atm
Cause honestly its screws with both teams having random weird low skill pos4 players.
Go look at any 4K trash mmr replay and you will see this in 90% of games.
Source: https://www.reddit.com/r/DotA2/comments/sg8172/the_biggest_problem_with_low_mmr_games/