The benefits you get from using this site (for me at least) are:

a.) glitched times and scores are deleted if they are obviously impossible (lap times of 14.xx on venom class, or race times of under a minute).

b.) the wonderful Matrix feature lets you know in a plain, unmistakable way which tracks I need to improve my time on. Just generate a matrix (for either score or rank) and check where you're ranked low or score few points on, and go for that track. It helped me improve a lot in a short amount of time.

c.) You can't use various sorts in the in-game records tables and only a limited amount of filters are available. It takes much longer to get the info for questions like "what rank am I on this and this track among only Goteki 45 pilots?" in-game.