I dont believe you can compare top drivers with more common drivers. I think that most people will agree, that flex might be an advantage for beginners. However, when the hot shots goes with stiff chassis', then beginners will look at that, and go for carbon fibre.
I've seen really many beginners, which aint got the patience to learn thing with a beginner friendly car. Not to mention the classic example, of beginners, throwing in a hot motor, which they cant handle.
I read somewhere that Hara actually did a lot of this stuff, to increase and reduce flex.
Lets assume that flex actually is an advantage. Then HPI had the challenge, convincing people that flex is an advantage. Simply because the message are unclear.
Dont get me wrong. Personally, I believe in a stiff car, especially on carpet. However, I may admit that I dont truly understand this flex issue.
Schumacher Mi5 - Sanwa MT-4 / RX-462 / KO Propo PDS-2123 - Nosram 5600 X-treme Saddle Pack - LRP SPX Zero/X12 17,5 - Nosram Stealth Touch Evolution - MAAS SPS 9250