If someone is having fun by quicksaving and reloading to get the optimal solution, why deny it to them?
Well, my argument is that it isn't fun. Do you think it's fun? Do you know anyone who thinks its fun?
My argument is that people are going to play to win, which doesn't necessarily mean playing for fun. As a game developer, I feel it is my duty to make winning fun.
Also I am not sure you understand grinding. Quicksave abuse is savescumming, which isn't really grinding so much as rigging the slots in your favor.
Well, before we start some definitional arguments, I'll lay out my definition for grinding and see if you disagree.
Grinding -- A repetitive act that allows the player to reduce risk in other parts of the game.
It's a broad definition, but I feel it fits.
And as to why I think that quicksave abuse, savescumming, is grinding is that it fits my definition.
e.g. In X-COM, I can take the time to save after every single step. This will reduce the risk that my party gets wiped due to some fluke, but at the cost of wasting a lot of time and fun for me the player. It isn't fun for me to do this, but it also isn't fun for my team to get blown up on the first turn.
I know that savescumming isn't grinding in the traditional "I'll kill 1 million boars to level up," but I feel that it is just a different in the mechanic being abused. One abuses a bad leveling system and the other abuses a bad save system, but both have the same causes (poorly balanced game) and the same symptoms (player taking a repetitive action to make the game easier).
When you start saying that users shouldn't be allowed to save anywhere, you are outright dictating the pace of the user's experience as well as what session times will be. Users hate this.
I strongly disagree. By creating the game, you are dictating the everything about the user's experience. If I want to dictate their pace, that's my prerogative. Now, whether I do that well or not falls on me, but throwing up my hands in the air and saying "Wow, it's hard to pace this properly. Well, I'll just let the user do it." smacks of defeatism/laziness. If the developer does their job correctly, the dictation of pace/session time shouldn't be a problem.
Also, as mentioned, manual saving allows players to revisit sections of a game that they necessarily don't want to play all the way through the game for. For example, before each major branching speech interaction in Deus Ex: Human Revolution, I perform a manual save. That way I can see both sides of the coin without being forced to play through a game which has no relevance on that decision.
This is probably the closest I would come to agreeing with a manual save solution, but the game knows when a big decision is about to made. Wouldn't it be better for the game to seamlessly create a save (or have some sort of chaptering system) such that when you hit a point like this you wouldn't have to do it yourself? What advantage is to be gained from forcing the user to do it? I only see downside.
Why isn't this reason enough?
Maybe I wasn't clear. I strongly agree that there should be the pause/restart save (or whatever the save should be called that allows a player to say, "Welp, I'm done for the night" and then can restart at that exact spot, but it is wiped when the player restarts). I understand that no checkpointing system will be perfect and that it is supremely annoying to force a player to reach the next checkpoint to save (particularly for mobile games when play session length is not directly in your control).
The reason I think that sort of system is good is that it isn't abusable (except for extreme cases of players subverting the intentions of the game by messing with the file system), it allows them useful capabilities, and it doesn't mess with the intended pacing of the game.