If you are refering to QM , i have just one word that explains it all - EXPANDING . Yes , expanding feature in QM that searches in lower MMR groups of players just to fill all slots/roles needed was the final nail in the coffin .
Since i use it to play whatever hero i want and not get bored to death to fill in HL /TL i see it ruins every game .
EVEN when every game in QM was 5v5 assassins was better than this EXPANDING . Today i had game vs a player who was Johanna and his acc was lvl 8 . He basically started the same DAY . He never mounts , barely moved , skill usage made him stood in place for seconds , was running into towers forts (obviously new and not knowing which planet he landed ) . A LEVEL 8 PLAYER , and my acc is 1820 Come on …
Otherwise , i have hundreds of screenshots of thigs like this guy happening . Usually some of the players that are with me are in the range 100-200 .
They do all the wrong things you described . Dont soak , fight till death never backs to heal only if killed , doesnt care about any Talent advantages whatsoever , LET ALONE HEROICS :D, contest objectives with no mana , no health , Camps are something mythic ( they only heard of it , never capped one ) , pick all wrong talents required to counter the specific enemy team ( some are gamebreaking like Hanzo not picking Arrow or Varian solo war goes Colossus vs Garosh on the enemy team ) .
Sorry for the wall of text , but this will keep happening until they remove the EXPANDING . I already began EXPANDING to a different game ( still playing Hots tho ) , soon to be perma gone.