[TeMPOraL]

Reality: sleep training enters the picture only after all the things you've mentioned have been checked first.

Even from a pragmatic point of view, it's hard to imagine otherwise, because all of those underlying reasons are quick to check and (usually) quick to mitigate. You don't even consider sleep training until exhausting every other option, because literally everything is easier than any of the sleep training methods.

[lern_too_spel]

All of those things have to be checked immediately every time they cry. The Ferber method, mentioned elsewhere in the thread, says to not even check on the baby for longer and longer periods after they start crying.

During the daytime, if they start crying and you haven't solved the issue, you don't just start ignoring them. Why would you do so at night?