I have hardly any time for Internet nowadays. I will just be making a few comments here because you specifically tagged me.
As regards the title of the thread, it is too vague and does not specify what it means by "ruin". In terms of social/economic factors, we cannot say that Islam itself had a ruinous effect on Afghanistan before the 1980s. It terms of cultural factors, you could say that Islam made Afghan culture much more oppressive especially with regards to women. The 2nd century Assyrian scholar Bardesanes writes that Afghan women of Kushana age wore the same clothes as men, rode horses and carriages in public, and had no compulsion to be chaste (he states that some Kushana women even bought male slaves for sex). Even if these are exaggerations, it is probably true that Islam made Afghan society much more patriarchal and limited the freedoms of women. One cannot imagine Afghan women of the 13th century acting the way that Bardesanes described one thousand years earlier.
However, if you are talking about art, literature, architecture, and other aspects of "high culture", then Islam definitely did not ruin Afghanistan. Indians may hate Ghaznavids, but it was under their patronage that the
Shahnamah, the greatest piece of Persian literature in history, was composed, and it is for cultural achievements like this that Ghazni is praised by Afghans. We also find many architectural gems from Islamic Afghanistan, which in my opinion rank among the most beautiful buildings in history
You can hate Islam and Islamic values if you wish, but you cannot say that the people who built structures like these were mere barbarians with no sense of cultural refinement: