Why? You should let each post stand on it's own merit.

First, account age is silly for Lemmy, as almost 100% of people on here will have an account creation date in June 2023 or later because this place was a ghost town before Reddit decided to kill the APIs. A month from now, is someone with an August 2023 join date automatically presumed to be a troll, or are they just someone making the switch from Reddit a month later than everyone else?

As for karma, neither negative karma nor positive karma really tell you anything about the poster:

For instance, people can make good faith arguments advocating for conservative political opinions, but because the user base skews pretty far left here, those arguments will be downvoted. A discussion forum that bans opposing viewpoints is useless, and the echo chambers on Reddit are something I'd love to avoid here.

Similarly, it's also possible to effortlessly build positive karma. Simply copy/paste highly rated comments from the last time a common repost appeared on the feed, and chances are, your copy/pasted comments will get upvoted too. You can even automate it with a bot.

Karma meant nothing at Reddit, and moderators shouldn't be using it for decisionmaking purposes. It's useful for ranking posts and comments, but anything beyond that isn't helpful.