There are some things computers are really good at and that human beings also enjoy doing. Computers are insanely fast, yet plenty of reflex-based games exist. A lot of high-level competitive games have a dexterity dimension. FPS games for example are a mix of strategy and dexterity, with a big emphasis on dexterity. RTS games like Starcraft put a bigger emphasis on strategy but still require insane finger dexterity at the highest levels. The dexterity part of the game could be done far better by a simple AI. Aim bots in FPS or inhumanly micro-management in RTS have been demonstrated, yet those games are still played, and interesting.

One of the examples you gave, Hearthstone, actually had many bots running on the ladder for a time. Their goal was grinding, but even so, a number of them was better than a significant portion of the human playerbase. With the recent advances in artificial intelligence, computers are not that bad at this kind of task.

Overall, I don't disagree with your main point though. I have no qualms automating boring and repetitive tasks in non-competitive games. And if a competitive game has those parts, I'd probably avoid playing it. I'd rather spend my time coding than wasting it grinding because it's part of some game I otherwise enjoy. I feel it is indeed a more productive use of my time. I wouldn't go as far as judging other people who like the grind though.