If a logo produced by a single employed designer or firm is better than a logo produced via a 99designs-style contest, then you're going to have to prove it instead of merely claiming that your way is superior. The Stack Overflow logo doesn't seem to be missing some sort of je ne sais quoi that a non-contest logo would have. I'm also happy with my 99designs logo. If I'm hurting my business with such a logo, I'd appreciate some sort of proof.
Otherwise, this seems to be an argument about maintaining designer wages, and I am rightfully not concerned. Everyone wants their wages to go up and the prices they pay to go down.
I'm not claiming your logo is objectively detrimental to your business, just as I wouldn't claim that off-shored software is objectively detrimental to an offshoring client. I've certainly used software developed by a small team in India that did exactly what it needed to.
I don't know what your logo looks like. It might be a great piece of design that connects with your customers and represents your business well. All I'm saying is that a proper design process helps ensure that happens; it's no different from software in that regard.
Otherwise, this seems to be an argument about maintaining designer wages, and I am rightfully not concerned. Everyone wants their wages to go up and the prices they pay to go down.