Providing obvious, useful functionality has no more relationship to the concept of a cargo cult than providing a cup holder in a car.
Don't deny your users the 80% (more like 99%) case just because there's a complicated tool out there that, with a bunch of bloat and UX problems, can also provide the 20% (1%) case.
Following whatever 37signals does is what seems like cargo cult. They do so many things wrong, and yet designers like this come and say "If they are doing it that way then it must be the right way".
Don't deny your users the 80% (more like 99%) case just because there's a complicated tool out there that, with a bunch of bloat and UX problems, can also provide the 20% (1%) case.