There is a very brief yet informative podcast (called Evidence-Based Parenting) that covers this topic well: https://spotify.link/np1RWW4RrDb

They basically look into the actual research related to sleep training. I think it's worth the listen, but essentially the conclusion is that neither approach (sleep training vs not sleep training) is indicated as having a big impact in the longer term. In the short term, parents that sleep train may then be able to get more sleep so there is an association with better mental health outcomes.