Well to start with your cite thinks the steel in the building melted. It didn’t. The floor joists sagged under the weight of the concrete it was supporting due to the heat. That pulled the vertical supports in until the weight above caused them to fail.
This is what the evidence shows. You seem to be suggesting that ninja’s sneaked into the buildings and planted explosives without anyone knowing it and then relied on people who never flew a commercial airliner to hit the exact spot so as to look like an accident. They then waited for a half hour or more to blow it up to further confuse people into believing a severely damaged building with a runaway fire might collapse.
What would constitute a “real investigation” to you? There have been dozens of studies carried out, and time and time again, without fail, your ilk declare the people involved to be “in on it” because it didn’t produce the results you wanted to see.