First of all, the community around LW2.0 can only be loosely associated to a movement: I don't think there's anyone that explicitly endorses *every* technique or theory appeared here. LW is not CFAR, is not the Alignment forum, etc. So I would caution against enticing someone into LW by saying that the community supports this or that technique.
The main advantage of rationality, in its present stage, is defensive: if you're aspiring to be rational, you wouldn't waste time attending religious gatherings that you despise; you wouldn't waste money buying ineffective treatments (sugar pills, crystals, etc.); you wouldn't waste resources following people that mistake fiction for facts. At the moment, rationality is just a very good filter for every product, knowledge and praxis that society presents to you (hint: 99% of those things is crap).
On the other hand, what you can or should do with all the resources you're not wasting, is something rationality cannot answer in full today. Metaethics and akrasia are, after all, the greatest unsolved problems of our community.
There were notorious attempts (e.g. Torture vs Dust specks or the Basilisk), but nothing has emerged with the clarity and effectiveness of Bayesian reasoning. Effective Altruism and MIRI are perhaps the most famous examples of trying to solve the most pressing problems. A definitive framework though still eludes us.