Why do you say there's a bias?
I'm pretty sure if you asked those posters why they generally prefer the Giro or the Vuelta over the Tour they'd be able to come up with some thorough explanation.
Okay. Here's why I think there's a bias.In your opinion, what is a good bike race, and how has the Tour been a better bike race than the Giro over the past decade?
Most here also think that Paris-Roubaix is a clearly better race than Liège-Bastogne-Liège, but is that down to some hipster bias, or is one of the races just better than the other? If you expressed an argument that can be engaged with, it's possible to have a far more meaningful conversation than just taking turns dismissing others' opinions as bias.
Favourite GTs seem to be very influenced by favourite riders. Nibali, Valverde, Contador and also Basso make the Giro and the Vuelta more popular to a degree because of that. They also did well in the Tour, but the Tour is not "their" race. The Tour is more a race of some riders who are unpopular here, recently of course especially Froome. (I guess at the height of his successes there were many more Froome fans around, but many vanished?) The results in the GT elimination game seem to suggest that a GT without Nibali, Valverde or Contador in the Top 3 is regarded as bad. This take has flaws of course, you probably say those riders make a race interesting as opposed to Ineos, and that a good route brings out the best riders on top... But usually my intuitional take on such statistics is not bad, so I'm going with it.
In many posts, I don't want to go through the threads now, I think you read them just as I do, there are very openly opinions expressed, such as "a GT where Froome does bad is a pleasure". In many posts I read "the casual viewer", "the normal viewer" who likes the Tour, who only watched the Tour, who does not know about things...
That Ineos and Froome tend to strangle the Tour is a fact, but for instance Alaphilippe is regarded as a rider who only does things to impress the casual viewer who does not know anything about cycling, while I think that if you love attacking in cycling there is hardly a rider you would have to love more. But the association "for people who do not know stuff about cycling" puts you off. You would be excited by the prospect of van der Poel taking part in the Tour, but the van der Poel and Evenepoel-fans seem to be a bit separated from the GT-fans.
I feel there is a field of associations "Tour - for the average viewer - Ineos - bad route" rather than a neutral take.
Then there's expectations. It was already expected that the Tour route would be bad, while the expectations for the Giro route are way more neutral - you can say you are used to bad Tour routes and therefor it's only natural, but I think if you expect something in a way, you are more inclined to find what happens to go along with your expectations.
You have gloated about how fun it is to bash the Tour route and that you are in this together, which forms a sense of unity in a community. Understandable, but does not smell unbiased.
LBL and P-R are races that are about equally hard to win, they are just suiting a usually different type of rider. P-R is more "exciting" because all the action happens at a certain part at LBL, but that really is only because the route is different, not because the average quality of the riders or the strengths of the teams is a bit weaker.
Puh, I'm going to stop here. Are you really saying you are not biased? I mean, Red Rick openly acknowledges his against Ineos and Froome and loves to play with it, I kind of assumed something similar for others.