I would tend to agree with Missaberoad on most of this.
My thoughts...
1. The biggest question/problem is "what is an individual's threshold as to what is prototypical?" Going down the MFCL rabbit hole is indeed a real "danger".
There was a time that N was ruined for me until I had better perspective on things. Now I don't sweat the small stuff too much anymore. "Opportunistic" is the mantra for me now...sometimes I'll bite on something I know isn't within my overall desired threshold. Good example is a nicely weathered MTL car, and this UP car was tempting. But I am more likely to let a known foob float on past in an effort to save money/space and otherwise try to keep things as proto as is reasonable.
2. For those reasons, I'm against the "tag". It would hinder sales to people that really wouldn't know (and deep down probably wouldn't care) otherwise.
3. The complication here is that many releases have a short window for making a decision so there's not always time to do the research. (With MTL items, that research is literally handed to you on a platter within a week of the weathered releases.) But I suspect the frequency of that being an issue is extremely low.
As an aside, I think the "Hypotypical" type products are a completely different realm. Same general style of releases have been done my Intermountain, Athearn, et al. I know there are similarities but it seems different to me on a number of levels, one of which is that locos are much more popular and identifiable.
