In my opinion, the FX rifles are so prevalent because they perform well in so many areas. What I mean by this is, they are suited for competition, hunting, plinking, etc. For example... You wouldn't take a Thomas rifle hunting. It's not designed for that and would be uncomfortable. I'm not at all suggesting it wouldn't put the game animal down, but it just doesn't fit in the hunting scenario. RAW reportedly makes a very accurate rifle. But I also hear that they can be on the heavy side. So, there's a rifle that would shoot very well in comp, and still be capable of going out into the field. Of course
you could enjoy plinking with either of those but, if you think about it, would you really want to? And, if you did, would it really be as enjoyable?
Again, this is just my opinion on it... FX seems to bridge the gap by putting out rifles that "fit" well in many areas, including competition. My own personal R400 is a perfect example of a rifle that I used for hunting and plinking (for joy) over the Summer and then packed up to compete with at EBR without making any changes other than the scope. The Impact is another example of a rifle that can be used successfully in many ways. Obviously, competition is one. It's short frame and power/caliber changing makes it very capable in the field. And, in quite the opposite configuration, it can be used for plinking smiles onto faces. I find the Wildcat to fall in this category as well with the additional benefit of being light weight and easy to load. Would a Cricket fall into this category? Yeah, probably. And, I've seen them at EBR. Edgun? Yup, I've seen them too. Air Arms? Yup, brought one years ago. I keep coming back to FX because their rifles do everything I want them to and they continuously do it well.
True, the manufacturers want a good showing and also want to try out new concepts and want to see their name all over the place. Lending a rifle(s) to a good shooter(s) to compete with increases your chances of getting your name to place well in the event. Makes perfect sense. But, that doesn't explain all the shooters that show up there. I think the numbers of shooters in that category makes up a very small number in the whole event.
Anyway... That's my take on it.
Cheers!

Tom