List of Tested Games
Why don't popular games like CS2, R6S, and VALORANT support 8000Hz?
Because the honest truth is that hyperpolling is a gimmick that introduces more problems than it solves. Most engines flat out aren't designed to handle data input events at such a high rate, in some engines, you'll be faced with a data choke that causes the engine to ignore the excess commands, in others, you will face performance issues (for example, lower fps and stuttering issues as internal threads get overloaded), in other scenarios, you will see intense CPU usage.
It's true that hyperpolling mice do produce a smoother and far more accurate input signal, the only thing is that the benefits of that are highly questionable past a certain point. Most engines' sweet spot is between 250 to 333 Hz; with some competitive games usually optimized up to 1000. Above that you're on your own and I hope you have an equally high-spec PC to handle it.