That would make sense, but in the game, it already shows how you place on the leaderboards of the gams, so it wouldn't make any sense to put it onto speedrun.com

There isn't mk8D times in mk64?

No.

Plus, MK64 only saves ghosts whose runs don't go out of bounds.

This has been answered numerous times and in the FAQ section of the forums that is sticky'd so you shouldn't have missed it. https://www.speedrun.com/mk8dx/thread/etl7j To quote Pianist; "Q: Why isn’t there a leaderboard for individual tracks or time trials? A: Several other sites already keep track of time trial records, such as this one: https://mkwrs.com/mk8dx/ and this one: https://www.mkleaderboards.com/mk8dx and this one: http://www.mariokart64.com/mk8/ and this YouTube channel: https://m.youtube.com/channel/UC_292L5mAJowD4LCCNZRbHg. We would be heightening the redundancy even more my having our own leaderboard."

What's the point if there's a site that tracks every ghost and every video from every Mario kart track World Record? That's my view tho