To put it colloquially: Aikido doesn't suck. However, if enough people say Aikido sucks over and over again, it eventually becomes subliminal, a sort of knee-jerk reaction. Example: all politicians are crooks & liars. Although there are many politicians who are indeed crooks & liars, not all of them are. In fact, many are honest and hard-working. However, it is indeed engrained in our collective subconscious to naturally distrust public officials. Get my point?
In other words you're talking about are meme's. The meme "all Politicians are crooks" has been around since before the founding of the Republic and is well ingrained in the publics mind. The meme "Aikido sucks" only exists on a few websites, and in All the UFC/Pride/K-1 I've watched over the years I have never seen any professional fighters speak too badly or loudly about any Gendai Martial Art including Aikido in the mainstream media.
I will agree though that these days when some idiot in power says there was a link between Al Qwacky and Saddam and another says Smoking Mushroom Cloud enough times a certain percentage of folks will believe any lie any authority figure tells them. The Big Lies often work for a time, even though they are refuted over and over again by the facts. That can be the true power of modern internet based media. However without a huge amount of coverage in other forms of media and a certain amount of visual factual evidence/annecdotes, the meme "Aikido sucks" will never gain enough traction to overtake the meme "Aikido works" since there are 60+ years of multimedia and facts to support it.
Thankfully most folks who have viewed the website(s) in question can descern the blowhards from the few professionals that are on those sites.