1) Because "support gun" is largely a fictional narrative in airsoft? You're either firing for effect and getting hits, or you're just blasting bush and your target likely doesn't even realise that you're shooting at them, let alone that in your head, they're supposed to be both impressed and suppressed.
To be clear I'm not criticising people who enjoy whacking the bushes, we're all playing a daft game of pretend for fun. But if your site doesn't run different rules for different toys, then the reality is a "support" gun is just a cumbersome carbine.
2) Don't we all like spending money on our preciouses and fiddling with them for that ultimate / imaginary extra 5m of accurate range? Heck, I'm currently running a Maple Leaf rubber and nub in my MP5K that over-hops the 0.2g that I feed it for CQB.