I don't understand how this is supposed to solve anything, and I've seen it suggested as a solution multiple times. If you restrict comments to older accounts, all it's going to do is make the bot creators speculatively open and proactively age accounts for future use.
This already happens now. Go look through a few of the "Show HN" authors - you'll inevitably see around several accounts that are 50-100 days old with a karma of 1 to avoid a green label.
The OP is talking about posts, not comments. The simplest solution might be to prevent someone from posting a "Show HN" until they’ve earned twenty-five or fifty karma, to demonstrate that they’ve been actively participating on Hacker News rather than using it solely to promote themselves.
I wish for karma based too if we managed to get filters. I want to see posts only by accounts with {x}+ karma points.
And also invest more effort in karma farming. In other words, if we raise the bar for Show HNs we'll probably see more generated comments in the threads.
Several of the posts I've seen are from autonomous AI agents, which don't currently seem to have that kind of long-term planning.
I don't understand why we put locks on bicycles, a determined person can just saw them off.
My prediction is that nothing short of human verification is going to solve this.
I would argue that we shouldn't let the perfect be the enemy of the good. Adding a cost to commenting that requires aging accounts I think might discourage fly by night operations and "experiments".