Yes, I think they are, as a short answer.
The term was institutionalized by the CIA in their declassified memo calling on CIA assets to discredit opponents to the Warren Commission.
However, instead of your Wikipedia definition (which can be edited by the CIA or anyone else for that matter), I like this one better:
http://www.sott.net/signs/conspiracy_theorists.htm
I don't believe in all conspiracy theories, such as 9/11 (although I believe that 9/11 was used as a pretext for a bullshit war), but I do believe that the JFK Assassination is the result of a conspiracy.
The House Select Committee on Assassinations (HSCA) concluded:
https://www.archives.gov/research/jfk/select-committee-report/summary.html
There are many serious researchers, investigators, scientists, etc. that have examined and studied the facts surrounding the assassination, especially with the release of thousands if not millions of pages of declassified files after the passage of the JFK Records Act, following the controversy after Oliver Stone's movie
JFK. The remaining files ares supposed to be released in October 2017 (yes, this year) unless President Trump has a very good reason not to, as prescribed by the legislation.
Now if anyone believes that Lee Harvey Oswald, a "lone nut", killed President Kennedy, then why the fuck did they classify so many intelligence files?!? The last files to be released, include some of the CIA's most important spooks, who are all dead now. Will we ever find out the whole truth? Probably not, but the plethora of circumstantial evidence that has surfaced or been uncovered since the days of the Warren Commission most certainly would've resulted in an acquittal of Lee Harvey Oswald if he had been brought to trial today (back then, a lot of info was buried - even by J. Edgar Hoover).
There's ample evidence to suggest that Lee Harvey Oswald was a low-level intelligence operative and FBI informant. As an example, a call placed by him from the Dallas jail to a John Hurt of Raleigh, N.C. is just one of many, many items of circumstantial evidence that calls into question the findings of the Warren Commission. There was a John Hurt who was a retired Army Intelligence Officer. According to Victor Marchetti, former CIA agent and author of the book, The CIA & The Cult of Intelligence, the CIA had a fake defector program in N.C. and that this John Hurt was likely a "cut-out", someone who acted as an intermediary between Oswald and his true CIA handler, as a means of preserving plausible deniability. (Oswald was seeking help, and when he didn't get it, that meant he was on his own, and probably a dead man after that).
Does anyone in their right mind truly believe that Jack Ruby murdered Oswald and expose himself to the death penalty in order to prevent Mrs. Kennedy the agony of going through a trial? The White-Wash Commission, er I mean, the Warren Commission, said that Ruby had no connections to the Mob, but the HSCA said otherwise - that Jack Ruby had SIGNIFICANT underworld connections. A report by an undercover FBI Agent, now declassified, has Carlos Marcello admitting to having JFK murdered. It's been postulated, based on available evidence, that the Mob with anti-Castro exiles and rogue CIA agents may have killed JFK but that the government covered this up.
Sorry for my rant, but my point is, that not all conspiracy theories are bullshit, but alternative explanations to major events, and that those who propose them, are not all lunatics.