Viruses.
Not just that but ads, if they used them. The bottom line is, if you know anything about computers, you know a PS3 emulator (that plays commercial games at any kind of decent speed) will take a long time to come out, and it won't be any time soon, if ever. The problem people have is in believing that because the SNES, Genesis, Playstation, DS, N64 and so on were relatively quick in development, that this automatically means every console will be.
And it simply isn't the case.
If you are ignorant of what goes on in emulation, then it is easy to think it should be possible "within 3 years".
10 years ago, I would have probably thought the same.
edit. From what I am reading, the "emulator" when downloaded actually directs you to numerous survey sites with the promise of a download link that never materializes. As would be expected.