The Good Place

I don't think the burden is meant to be any different than that for "materialism". That is, "materialism" is simply the term describing a variety of metaphysical positions that don't think "immaterialism" can describe all of reality. As I mentioned to Steve001 earlier, "immaterialism" is not used as "not materialism".

This is entirely false. Materialism has a positive definition, and is in no way “simply” a word that combines other positions stating that immaterialism cannot describe all of reality. 

Materialism, very very clearly, states that there are material explanations for all of reality. It is the one making the positive claim that it can describe everything. I don’t think that immaterialism (which to me is a broader term than materialism) claims that, necessarily, everything has an immaterial explanation (unless you mean god or a prime mover or something). 

But even if it’s fair to say that immaterialism IS saying that, it’s totally unfair and incorrect to try to act like materialism is not saying the same thing the other way. Otherwise, it’s likewise fair to say that immaterialism is simply a term covering all the ideas that don’t think materialism can describe all of reality. 

Immaterialism is often used to mean “not immaterialism”. There are numerous people here including myself who I have seen say “I just believe there is something going on beyond the current materialistic picture,” or something to that effect. It’s just totally false and unreasonable to try to make materialism seem like it is only encompassing a negative definition. It is very clear that that’s not the case, and that in general materialism is holding that material things can explain all of reality.

Again, if you don’t think that’s the case, there is no reasonable basis for saying that materialism is not like that but immaterialism is.