Try playing Dota or League without learning how to CS (creep-score, it's just a much easier way of saying "last hits/denies). You'll be stomped into the dirt.The enemy laner will have a much larger advantage over you, be able to dive and kill you multiple times due to that gold and level advantage, and then snowball into killing the rest of your team. All because you didn't think CSing was worth your time to learn.

I play far more Dota than I do LoL so I'll go with that. Learning how to CS properly is the very first step in learning to win your lane handily. If you cannot deny, the enemy laner will often be on level parity with you, which, if you are a mid means you have no advantage over the other mid, a carry means the enemy offlane will hit a power spike very early and in all likelihood, kill you repeatedly,a support means you can't stop the enemy offlaner from leeching XP from the wave you probably just pulled. You could be a god at creep manipulation, but if you can't CS properly you can't take advantage of that.

By stripping away a "needless" mechanic like CSing, Blizzard killed the ability for individual players to have much of an impact in HotS, and by giving the whole team shared XP, it turns the laning phase into a game of poke damage which you can hopefully turn into a kill at some point. It's just a bunch of people throwing trash damage at each other waiting for someone to commit to a kill. By stripping items away, no team can build a game plan that takes advantage of early power spikes (unless those are designed by Blizzard), or by sacrificing the resources of certain heroes on your team in order to help one player hit a power spike far earlier than they should. Blizzard built a fighting game with the trappings of a moba, that somehow fails to be as fun as either. Sure, it's great fun to play with your mates when you're a little buzzed on a Friday night, for the first hundred games or so, but if you're coming from another Moba all it's going to do is put you to sleep by the time you've finished learning what each hero does and how they interact with each other.

Blizzard has this tendency to strip away mechanics and systems which seem "unnecessary" on a surface level in a lot of their games, but all it really does is dumb their games right down to a level that makes them deeply uninteresting to play beyond a couple dozen hours. Diablo 3 did it to Diablo 2, Overwatch did it to TF2, Hearthstone did it to Magic, and HotS did it to Mobas. Sure it makes these games more accessible for new players, but once you get past that initial learning "curve" and polish, all you're left with is dull, repetitive games that you drop after realising it can't give you any more.