When I started Roux there were 4 users I knew, Richard Meyer, Peter Greenwood, Kir, and Roux.
It wasn't that people thought Roux was bad, rather just no one had really explored it at the time. No resources. Also our cubes were complete shite. Also a lot of us were ****ing elitist *******s.
It didn't matter how much potential a method has if there is no one to tap it. And without concrete evidence of achievable speeds why should I use that method? When I started Roux method was only 3 years old. But Roux himself had sub-15 official average, this was enough for me to use this method. But probably not for most people
So I would way that the sudden increase in numbers would be a result of people like Big Green, Arvind and Alex popping into the scene. Big Green had a big impact but it wasn't enough to really get the ball rolling and Alex kind of punting it to where it is now. It's just like how Fazzles dominates the nub population. Nubs want only to what the fastest do.
The school of thought with Roux. It's very very fun. The reason was in order to get fast you either had to make **** up yourself or wait on the 3 other people to make **** up. There were no real developments and all in all just turned into a circle jerk who just wanted to develop something so they could be plastered all over the cubing community as the guy who made "blah" (example MBR)
I feel like most cubers just feel indifferent about most cubing things unless it has solid proof of being good. People don't think good/bad/otherwise until then. Then you get good and people will have good thoughts (constructive criticism, positive appeal) bad thoughts (method insecurity, method fanboying, method shaming). These things only really come when a method already has traction and it did not back then.