You would be able to see what the leaderboards used to be at a specific date for a specific game.
The only thing I really think this would be useful for is for looking at WR progression, which you can already see in the statistics page.
If you truly want this, I’d recommend archiving the LB you’re interested in yourself (scraping it or using a web archive or something) because making automatic snapshots of the LBs on this site just isn’t practical.
The past run data is all there. Which is how the site itself constructs "WR progressions" using the best known times on the board.
Archived records are pretty important, especially for games that change drastically over the years like OoT. There are already tools to get this data though, mentioned above.
If you wanted elaborate boards, you'd need to limit it to discovery of major tricks or extensive route changes. Beyond that lies insanity.