They did this, and perhaps still do, to deceive researchers and people who are interested in the topic for one simple reason, to keep them away from the truth.
On top of these disinformation campaigns there has long been an "official campaign of ridicule and secrecy" (Roscoe Hillenkoetter, Ex CIA director) associated with the subject. But perhaps things are changing with recent revelations, but that’s another discussion in itself.
I'd like to draw your attention to Dr. Jacques Vallée,
who holds a master's degree in astrophysics and a Ph.D. in computer
science. The subject of UFOs first attracted his attention as an
astronomer in Paris. He subsequently became a close associate of Project
Blue Book's J. Allen Hynek and has written several books on the UFO
enigma. He is currently a venture capitalist living in San Francisco.
Vallée co-developed the first computerized map of Mars for NASA in 1963.
He later worked on the network information centre for the ARPANET, a
precursor to the modern Internet, as a staff engineer of SRI
International's Augmentation Research Center under Douglas Engelbart....<<<Read More>>>...