Can you incentivize grouping? Selfsih game.
This game has so many mechanisms that wrongly incentivize selfish play, that several games I lose despite stomping my midlane and taking first two turrets mid often happens that I'm getting either top or bot lanes that just want to split push without vision while the enemy team is grouped, or the top/bot lane is your typical Riven/Draven player who thinks that because they are 4/1/2 that they somehow can push their lane on their own or invade a warded enemy jg and 1v3 the enemy.
Sometimes bot lane shits the bed, and instead of coming over to my mid lane as I tell them to swap lane as jg can babysit them easier in mid, the ADC decides that he must avoid all teamfights and turret defenses because "I'm behind and I need the farm". There won't be farm for you if the enemy groups as 5 and takes mid inhibitor while you can barely scrape the first turret in your lane.
This game encourages such selfish gameplay by the heavy punishment of grouping, be it setting people behind in exp if they group or massively reducing gold income if they don't group up as a 5 man and take turrets (which by the way is losing gold as well next patch).
Top lane get stomped in lane by a single first blood or successful gank? He can't ever get back in lane unless he goes AFK farm some unattended lane and the enemy is not active in punishing over extension. The obvious answer of a Darius getting bullied by a Teemo or Quinn would be for him to move and help middle or bot or go team up with the jungle and do something, yet this game sets him even further behind in exp and gold for doing the only option available to him as he can't ever fight back against a laner he's died once or twice to.
I've played Heroes of the Storm and it's night and day the mindset installed on players. It's made very clear to you that you should group and that objectives are a big deal. Sure, there's also split pushing, but the context is completely different as are the opportunity costs and effectiveness.
This game just feels awful because half the games you're begging people to take advantage of the gains they've made on opponents and push it as a group, and they'd just rather chase pointless kills and have our single tank split pushing while the rest of the team gets dismantled 4v5 without a frontline trying to defend turrets or contest dragons/baron. ADC's solo pushing for farm without vision and especially with an assassin mid/jungler on the match.
This game should take better strides toward rewarding grouping and cooperative play, not this current state in which every player is an island obsessed with their gold farm to the point where a jungler sees you getting dove under turret or the enemy bot lane taking down mid turret and he'd rather finish a camp over helping contest the turret assault or pushing a wave out.