Store championship level and above is when I personally stop giving much missed opportunity leeway, and I expect none in return. The leeway I do give is for immediate errors, like saying "Go ahead" followed immediately by "oh wait, action" within about half a second and before I've made any game state changing reveals. Denying immediate correction would put the denying party firmly in the jerk category.
I think people white knight for the forgetful far too often for premier level events. Really, it should be the other way around. It is just plain rude to ask for missed opportunity leeway at this level. It puts the opponent in a very awkward position. It is incredibly unsportsmanlike to get huffy and call someone a ****** when they tell you no.
Store level before championships is a whole different beast. I see store players as members of my team. Those games are practice games for the championships and beyond. In those games I am much more likely to remind about missed opportunities when I see them being missed. This is a health of the game thing as much as anything else. You don't want to be scaring players off from your local store if you want to keep having a healthy community to play with.
I used to judge for WoWTCG for UDE. They had an interesting rule about game state for mandatory events. Both players were responsible for maintaining the game state and missing any mandatory event was a punishable offence. That means you could get warnings or game losses for forgetting that Rebel Captive you just shot at. In practice this rarely came up, but judges were expected to punish both players equally for such missed effects at premier level events. I rather liked that rule and it has affected how I play all games since. Mandatory game state is everyone's responsibility. Optional triggers are the responsibility of the deciding party.