I have no problem with mappers connecting the past to the present in OSM. The past always lingers in some form. I contribute to both OSM and OHM simultaneously, often mapping two aspects of the same feature in tandem. In this manner, the two projects strengthen each other.
Ironically, the counterexamples you’ve cited include some types of features that the community chooses not to map, chooses not to map directly, or has a very uneasy relationship with. To the extent that we map any of these things, it’s because mappers have been able to make the case that they have some practical utility in a use case focused on the present. Case in point: giant time zone boundaries are technically verifiable based on a few signs here and there, and theoretically on a multitude of wall clocks, but practically speaking they’ve all been mapped based on a close reading of the legislation. For these boundaries, the issue of verifiability is really a distraction. It doesn’t take a lot of imagination to come up with the real justification, that these features are useful on a general-purpose map; indeed, they’re widely used in time zone selector maps.
Unfortunately, every time the abandoned railway issue comes to a head, it’s a case where the railfan has already engaged in self-censorship in a futile attempt at playing by “our rules”. I do find that sad. If we were to allow them to fully map what interests them, what we would have is OHM. (Whether to merge the two projects would be a topic well beyond the scope of this thread, and a bit of the tail wagging the dog.)