I feel you're being a bit obtuse here. I don't know how you can acknowledge something like Gladio, a proven conspiracy, as historical fact whilst also assuming a default position of blanket dismissal when it comes to conspiracy.
I can't answer it, in all honesty, but the 'Strategy of Tension' was widely discussed
at the time and for perfectly plausible reasons. It was not a far-fetched theory, given the U.S. and NATO strategy in Europe. Technically speaking, the link between the CIA and the Italian far right terrorist groups has never been acknowledged or proven, but there is enough there to believe it was operational, both from the circumstantial, strategic and geopolitical context.
This is completely the opposite case for 9/11: the conspiracy narrative is totally nonsensical.