I wouldn't put O'Neill and McGowan in the same category. As we realized when McGowan went full 'actors theory' after the Boston Bombings in 2013, he imagines a lot of connections that either aren't there, or have no relevant significance. His Laurel Canyon series must therefore be critically interrogated. Many of the 60s musicians and actors McGowan suggested were 'instrumental' in government control/influence programs were 'guilty-by-association' in McGowan's eyes. O'Neill does what McGowan does not: drill down to the facts, and only then propose a tentative theory.
Agreed, now that you mention it, he does go on name-dropping and is tiresome following up the chain of names and events. Though it was the first time I had read about the military/intelligence connections of some of the 60's characters, only to be taken to a real investigative journalism level with O'Neill.