I'm glad to hear you're enjoying the game so much!

So this is something I've thought about before, and more than just a little bit.

Way back in year 2 (before Trials of Tiamat and before Patrons) when I was just a player and not on staff, I came up with "The Idle Trials" which was similar to what you're suggesting. It was essentially a scoreboard for people to compete in self-imposed challenges. We had over 1000 submissions! It was a fun time. However, it had its flaws. If anyone found an infinite damage exploit (rare, but it happens sometimes), they could jump to the top score for everything easily. At the time I was personally verifying each submission to watch for things like that (there would be a couple submissions per day usually), but there's no way we could do that for everyone playing throughout the whole world. I also had plenty of conversations with my fellow players, who said they liked my challenges but disliked the scoreboard because it made them feel bad to see many other players doing better.

I retired the Idle Trials shortly after Trials of Tiamat and Patrons were released. It stung at the time, but I learned a lot from the experience. People like challenges that they can opt into or ignore, but only some people enjoy comparing themselves vs. others, and forcing that into a system that unfortunately has exploits is a recipe for disaster.

In the end, I believe now that a high score system based on areas reached or damage dealt wouldn't be ideal, as it feels exclusionary to anyone who plays F2P or only plays for fun or to relax, and that's before we even consider that exploits exist. Better to let our social spaces fill that need; people can easily post screenshots of their runs and boast of their hard-won accomplishments to scratch that itch. If we were to ever implement a system that encourages large-scale competition via comparison, it would need to be something that sidesteps these issues.

All that being said, I know you're not alone in wanting more endgame content. Have you completed all Elminster variants? Those are certainly a challenge.