We've gone over it, but we never "reached" anything.

The thing is: Those (razed) railroads are not compareable againest, for example, razed buildings or even landuses. Because the difference is that they are part of a large interconnected network. They are also still closely related to the existing network - because they often played an important role in how it looks today. Unfortunately, this is all a bit complicated to explain. But the point is that good railroad data also always includes some basic data on former routes. 
I have 2 "professional" railroad map books at home, and they include every little abandoned branch line, even if it was only operated for a few years in the 1870s. (not from countries where I edit; don't worry)
And such data, which is just very strongly connected, should also be kept and maintained together.
 
If you look at the whole thing with e.g. buildings: A razed building is ...well a building, it is not directly connected to or dependent on other buildings. In addition, it has no relation to today's world. 
And if one would start now to map tons of random demolished buildings in OSM, then one would lose the overview very quickly; tons of data would overlap each other. On the other side, with a razed track: it is a single way, which should hardly ever trouble anyone.

I do agree with you that the vast majority of historic data one can think of dosen't belong into OSM. But railroads are a special case, and not just because I'm personally intrested in them, and also not just because they're rendered on ORM.
I've listed a lot more reasons at https://wiki.openstreetmap.org/wiki/User:Hiausirg/Razed_RRs

Further, I also don't really see why "only for ORM" should be that much of a problem, assuming it would be the only reason. It's not tagging for the renderer - that would be to intententionaly misusing tags for certain result i.e. landuse=industrial for purple flowerbed or golf path for normal roads. railway=razed is explicitly intended for "gone without traces".
The number of people interested in such routes is huge, the number of people using ORM (also specifically for such routes) is also large. So the data is -contrary to much on OSM- very actively used and helps people. And that while the impact/conflicts to overall OSM data is/are minimal.

It is not my intention to "go againest everything OSM is tying to achive", and i'm sure i'm not doing that.
My view: The "no historic data" guideline dosen't exist because historic data is sh1t, there is a deeper reason. That is, historic data can quickly lead to massive clutter and can become unverifiable quickly. However, these two problems are simply not present here.

Greetings