Re: Anthophobia
People don't as easily give up because of that. Doesn't actually make the bosses or anything any easier, just less mindless/boring content to repeat.
Actually, people give up on stuff pretty quickly if they're forced to repeat content; the vast majority of people will stop doing something in scenarios like this.
However, this has one exception;
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In cases like Dark Souls, if the player has become invested enough to get far enough into the game, they'll put themselves through levels of annoyance/repetition that would have normally caused them to quit the game, because they feel they've "sunk the cost" (in this case, time playing the game) into the game enough that to back out now would be a waste of "investment" (time).
That said, if the beginning of the game is this tedious, people will then usually do the reverse and back out long before they've invested significant enough time to have the above mental fallacy happen, and people who can push past early-game repetition/annoyance are the type of people who would generally not get dissuaded to play a game in the first place with high levels of repetition.
So the tl;dr here is;
-If your game is annoyingly repetitive for no good reason at the start of the game, it will turn many players away, besides the most hardcore gamers
-If your game is engaging early on, and not repetitive, it's a good strategy (if you want to be an asshole and exploit the human psyche) to make the late game repetitive/annoying, as people will generally invest more time into the game than they would have normally.
NOTE: the latter model is literally the core basis of all MMOs ever made that have been successful. Hook em early with easy, rewarding gameplay, then after they've invested 100 hours or so, just put their nose to the grindstone for thousands upon thousands of hours of repetitive, laborious tasks, all to get even 1/10th of the mental reward they got within the first 100 hours of the game.