I think the perception of popularity stems from what forums and resources you decide to browse and be a part of. If you just come to this forum, your perception will be skewed towards FX airguns primarily as the "king of the hill." Sure we discuss various airguns on this forum, but look at who sponsors each individual forum and that'll explain why certain brands or models are discussed more than others.
If you go to visit other airgun forums, you may see other brands highly praised and discussed. I personally have browsed multiple forums and sites that sell guns and read as many reviews as possible before making a major purchase.
Unfortunately like so many have already pointed out, a lack of brick-and-mortar stores nearby where you can go and handle a high quality PCP leaves many of us limited to our budgets when it comes to trying out guns. So if you have a limited budget you're not going to risk spending 2 grand on an EDgun when you can get an FX Impact or Crown or a beloved Marauder for much much less. This is classic "herd mentality." Stick with what you know. Case in point is the Marauder, both because it's inexpensive and highly accurate and has been around for a while.
Ultimately it takes a bit of financial risk to go buy that Taipan, EDgun, Kalibrgun, or Vulcan that you may have heard of, especially when the price may be prohibitive or the cost may be similar to an FX, Daystate, Brocock, Air Arms, etc that has hundreds of reviews and discussion threads. For example, if you saw PyramydAir, AirgunDepot, or some other big airgun distributor advertising Taipan or Kalibrgun on their main page like they do with Umarex or Air Force or FX, you'd likely be inclined to consider purchasing those guns.
I kind of feel like a rebel in a sense that I never fell for the FX hype, however great they may be. Instead I own more obscure brands like the Taipan Mutant, Kalibrgun Cricket, and now awaiting my EDgun R5 .30 caliber which should arrive some time early next week.
If overnight you had the likes of Ted or Matt Dubber or someone else exclusively switching to shooting with a Taipan Veteran, what do you think would happen to all the people seeing those videos? They'd likely be researching and or purchasing those guns just based on what they see - classic advertisement power.