The on-topic page says:
For the purposes of this site, "Islam" includes all groups that identify themselves as Muslim; do expect to see answers from multiple points of view unless a certain perspective is explicitly requested in the question.
which seems motivated by Why Sectarianism is Ruining Your Site where Aarthi writes:
For the purpose of this site, assume that each sect's hadith are valid, and that each sect's accepted imams are reliable.
Now I'm a mathematician, so when someone says all, I assume they know what that word means. E.g. it includes:
(Hypothetically) Self-proclaimed Shaykh Jeff McMuslim ibn Islam and his one-man Islam;
pro-X versions of Islam (where X is a random major sin); and so on.
I.e., I interpreted the on-topic page to mean literally "all groups that identify themselves as Muslim", no matter how few people the group has, and no matter how contradictory their beliefs are to mainstream beliefs.
G. Bach commented otherwise, suggesting a bunch of Islamic groups which might be excluded: Ahmadis, Bahai, perhaps universal Sufis, modernists and other ... heretical religious groups playing by different rules.
We just had a Baha'i-related question pop up: Do Baha'i consider Joseph Smith to be a Messenger of God? (now closed and automatically deleted as "RemoveDeadQuestions").
I guess we're faced with the trade-off: (a) be inclusive, and open the door to crackpots, or (b) be exclusive, and find a way to determine which versions of Islam are excluded.
Question: Are there any groups of Muslims excluded from Islam.SE?
For this meta post, I'm starting the dialogue. I'm asking if there's any group whatsoever ("that identify themselves as Muslim") that's excluded from Islam.SE. I.e., proof of concept that we wish to exclude some group that identifies as Muslim.
Relevant post from meta.Christianity.SE:
I think the absolute minimum bar for defining a "group" (sect/denomination/tradition, etc) would be two references to their existence, at least one of which has to be third party. -- Caleb ♦
There's also Should Mi.Yodeya/J.SE maintain its solely orthodox standing? and a bunch of linked posts.