It's weird, because I had no oil in the throttle body, yet I had HEAVY smoking after more than 2 minutes idling. I also had an unusually high oil consumption.
As A B Able truck said, once you work on those seals, you "normally" would replace every seal....
But there are people who tried mitigating the smoking issue by only changing the VCG and related gaskets/seals, and the end was only a reduced tailpipe smoking result.....
So I guess, there are situations & situations, and not a myth. Good for you if this worked in your case, but I would not encourage people to believe it's only the gaskets & related seals to only find out after doing this job, that the smoking issue persists (and you have now to re-do the job plus another one). I would also not encourage people to think that the valve stem seals are the only issue for a smoking N62 bimmer. The situation has to be diagnosed properly. In my case, it took me a longer time, without using scanners etc (which probably would have expedite the diagnose), but by driving that thing for months and opening up/closing different components and checking the state of them, plus some other random "tree shade mechanic" tests.

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Stable: e92is, e46 M54B25, e83 N52, e53 N62 - sold, e39 M54B30 R.I.P.