There is no need to have done something in order to be critical of it. Inference is exactly what makes humans special. I don't have to drive my car into a brick wall to be able to tell you that it's a bad idea. By definition something is irrational if it has no rational explanation, and thus no real point.
While some people may put non-functional spoilers on their cars (typically kids or young adults, which I don't think is a coincidence), they are typically ridiculed by people who "know better". You won't see a non-functional spoiler on the car of any serious racer at the track. In fact real racers remove everything that's not critical, including door/interior panels, carpet, air conditioning, and even the alternator for some. You won't see a professional competitive paintball player using a shelled gun, unless they are being paid to do so. You won't see an Army soldier running around with a shelled gun, either.
The reason some paintball guns are made to look like real ones, is because those manufacturers do have a rational reason, namely to sell it to people foolish enough to buy things strictly on aesthetics. If they can convince you to buy their gun over another based on looks, forgive poor performance because it looks cool, or pay extra over a similar model for cool looks, then you have played right into their trap (the trap to separate you from your money). One of the fundamental principles of marketing is to try to generate a need where there is not one, to make you feel that there is value in owning their product.
People would be far better off trying to shell a weapon that isn't going to interfere with their performance, like a console video game "blaster".
Feel free to PM me if you'd like to continue the conversation.