The problem isn't people who self-insert, it's the ones who carry that self-insert too far and stop seperating fiction from reality - they bitch about things that happened "to them", or the absolute worst that happens on these forums of people bitching about some fictional woman having sex in a game with other fictional characters that aren't "them".
I tend to call this phenomenon mirepresentation, but the sad reality is that some people act so fucking entitled that there is no reasonable approach that will work on them.
At the very least, in the discussion thread, as long as you are not offensive, you can post whatever you like and you will be subject to scrutiny/criticism. So when someone misrepresents for whatever reason, people can respond and set the record straight.
The worst part is when they voice their problems in the reviews.
Subtracting points for (random examples I have in mind)
- Lesbian intra-harem relationships where the game is explicit about it.
- More content for certain characters, despite them having a more prominent role in the story anyway.
- Prioritizing trap content for straight content due to story reasons.
- Violent/unreasonable protagonist, despite the game being explicit about it.
- Calling NTR when the characters in question have no relation to MC.
- Claiming that 2 tags are mutually exclusive, like Harem and Sharing, before even seeing the resolution of that content.
The problem is that you can't make any counterargument in reviews due to the medium. It's also unreasonable to report someone for misrepresentation. Not only it can be weaponized, but it's hard to prove that this is the case. Not hard in the sense that it's hard to prove it, but you have to make a complete argument, the moderator needs to be or be made familiar with the content and there is no guarantee that the direction of the novel won't change in the future.