Well, I am here since a long time, and I saw enough posters starting with 'no ISLAM = positive changes in future." And ideologically, there is many who do indeed this; darkening this legacy.
I've been on this board longer than you have; and it is quite obvious that there are idiots and bigots, on both side of the divide and whichever is the topic.
As a matter of fact this thread has been above average, and there has been no real ranting - up to now at least.
Still I fail to see where you come from, when you make statement like the one being quoted.
Do you mean that a world without Islam must be by definition worse than OTL? Why?
I would assume that out of the infinite number of possible timelines where Islam never came to be (not to mention the infinite number of timelines where Islam came to be, but did not last) an infinite number of them is worse than OTL, an infinite number is better and finally there was no difference in the degree of general happyness of humankind on an infinite number of TLs too.
Following your argument, it should not be possible to write a TL where the outcome is "better" than OTL. For whatever definition of "better" you care for, obviously.
A world without Rome would darken the legacy of the City; a world with without Alexander would darken the legacy of the guy (and possibly of all the Macedonians too

). I could go on but I think you can understand where I'm going: an AH board should be a place where new ideas and possibilities are discussed and explored; ideally even a place where one might find good and engaging TLs. However if there are a lot of taboos, if some possibilities cannot be explored, or must be explored forcibly according to an ideological prejudice, then I think it is not really the place I'm looking for.