Why didn't this company hire me? why did they invite me to see their facility in the first place, if they wanted to reject me? please read?

So a few weeks ago I had two phone interviews with an engineering company , my first interview was with HR which was by phone . They approved me , my second interview was with manager, and it was also by phone and they approved me again. A week later, they invited me to their facility and they showed me around the facility. I dressed nice , I was being friendly, the manager showed me the workplace. He didnt ask me any technical questions, and I was acting like I was interested, I was telling the manager thats nice and so clean, etc. I also asked manager few questions like what the hiring process was, what teams I will be working on , etc. I went home and two weeks later, I received an email, they told me that they hired another candidate. I was like what did I do. I have no idea what I did in that facility that I turned them off. If they wanted to reject me, why did they showed me their facility in the first place ?