May be oversimplification but I reason that this stems from the two cultures having opposed attitudes towards the "weird":
USA: focus on, make fun of, pretend niche is bigger than it is
Japan: pretend it doesn't exist, ignore
That may allow some Japanese to indulge in weirder stuff that would not be tolerated in the US, but what Americans may not understand is that this stuff is still seen as weird/non-conforming/shameful by most Japanese.
EDIT: Genuinely interested as to the reason for the downvotes. Plain wrong? Just stupid?
USA: focus on, make fun of, pretend niche is bigger than it is
Japan: pretend it doesn't exist, ignore
That may allow some Japanese to indulge in weirder stuff that would not be tolerated in the US, but what Americans may not understand is that this stuff is still seen as weird/non-conforming/shameful by most Japanese.
EDIT: Genuinely interested as to the reason for the downvotes. Plain wrong? Just stupid?