Many forums have a concept of a “stickied thread”, which is one that stays at the top of the list of topics permanently. I don’t know how good a fit that is for a forum designed like this, where there are very few visible topics, and also few subdivisions, but it does work well. It would be a good fit for things like the introductions thread.
I think LessWrong suffered from a lack of stickies—almost all the useful topics you posted saw extremely rapid declines in visibility as they dropped off the front page, which makes them effectively useless. The ones people liked—open threads, media threads, introduction threads—had to be reposted regularly for this reason. There’s no reason why a stickied introduction thread can’t last for a very long time (i.e. until it becomes unreasonably large).
A decision can be hard because the possible outcomes are finely balanced in expected payoff, or because you are quite lacking in knowledge about the possibly outcomes and/or their likelihood. If it’s the latter then it can be hard and matter a lot! For effective altruists there can be a bit of both. “Should I buy this pen or this other one? A better pen might help me write more effectively!” is probably the former, but “What career should I choose?” is probably the latter.
Plus, the latter kind of decision holds the promise of high value of information. If only you devote a bit more time to thinking about it or researching, you might improve your estimates a lot (or not). So that’s another incentive to worry about and delay such a decision.