I certainly have no interest in coercing any other group into my preferred B&R schema, but I will emphasize that I think Ice Age Old School formats are better for NEW groups with Necro restricted.
NOT because Necro is too good or can't be beaten, but because without Necro restricted, the other Ice Age tactics do not get as much oxygen. In our environment, there were multiple Land Tax/Brainstorm/Zuran Orb decks. There are combo decks with Glacial Chasm. Recursion decks with Forgotten Lore. And I played Reanimator.
Those decks are still really good even in a Necro environment, but with Necro unrestricted, the format becomes much more polarized into: 1) Necro decks, 2) decks that beat Necro decks, and 3) other decks (usually, that lose to Necro).
As I've said before, it's up to each group/community, but I feel that the communities that permit unrestricted Necropotence are applying B&R list standards used in competitive formats, like Vintage. As a causal format - and especially for groups exploring Ice Age for the first time - I think it's more important to give other strategies room to breathe.
Lest you think that restricting Necropotence "defeats the purpose of Ice Age," I will attest, having loaned out a Necro Weenie deck, that restricted Necropotence comes up frequently. Because these games are pretty slow, I'd say that even as a singleton, Necropotence comes up at least once every match I've played with mono black.
Necropotence is a powerhouse, even restricted, and playing with Restricted Necropotence in Vintage does not reflect how frequently it arises in Old School, a much slower format.
But if you are a group with deep experience in Ice Age, and aren't exploring the possibilities in the format, then I think unrestricted Necropotence makes alot more sense. But I promise that unrestricted Necropotence definitely undermines the exploratory potential of Ice Age.