If there were some well-known resource that records and validates scores, it would be trivial to just quote that resource as an answer. It would not be useful and it would essentially indirectly be asking for such a resource (which is off topic).
If there weren't some well-known resource for this, the answer might be hidden in an endless stream of YouTube videos, Twitch streams, etc. (of greatly varying quality).
- That basically turns it into a scavenger hunt, which just feels like it doesn't belong on a site intended for expert answers.
If that isn't compelling enough of a reason, it might be extremely difficult to validate any given answer, as in to make sure there wasn't any cheating, tool assistance or game modifications involved.
The speed-running community seems to deal with such problems quite well, from what I've seen. But there are a lot of people voting on here that wouldn't have the necessary expertise, or time, to detect these things. It would be quite easy for upvotes by them to trivialise the downvotes and comments of those who do have the expertise, if they finally get around to analysing the game run.
It might make a bit more sense if those experts could delete the answer, but currently that's something only mods can do and it wouldn't really be their place to handle these cases (either they'd need the expertise themselves, which isn't a realistic expectation, or they'd need to just blindly trust others, which somewhat defeats the purpose of electing them in the first place).
Also, gaining this expertise can take a lot of time for any given game, so opening the floodgates may leave the majority of less popular games without anyone with enough expertise to validate any given answer.
It probably needs to be video proof of the game run, since just an image of the final score would be easy to fake. Thus the proof will need to be offsite. Since they'll be quite dependent on this, that wouldn't be great as Stack Exchange answers should aim to be self-contained.
It also wouldn't fit all that well on the site as post score, and thus ordering, would become mostly meaningless as the highest score is automatically the correct answer, but any new answer posted (with a higher game score) will have a hard time competing with older answers featuring a lower game score with a high post score. The only reliable way to get them to the top would be through acceptance, but we can't really rely on the asker to still be around to do that.
In some cases there may be some great story behind a well-known top score of historical significance for a well-known game, which could make for a useful and interesting answer. But these will likely be overshadowed by many much less useful answers that can't say much more than what the score was and provide a link to proof. Overall, it probably won't be worth it to allow that.
In conclusion, it probably shouldn't be on topic.
Close reason? *Shrug*.
... unless the question is just asking about the theoretical maximum score. That might be fine if there's an analytical way to calculate or approximate that in that specific game.
Focused questions about how to get a greater score may also be fine, like ones about specific strategies to use in a certain areas or situations.