What if I know I'm bad at something and decide to hire someone who's a professional in this area? And this person does an amazing job. I want to endorse this person to acknowledge the obviously great skill he possesses. But I can't. My skills are not similar.
Also, do note that you're not really able to judge whether the work is professional or not. You can judge whether it works well, but for all you know the behind-the-scenes stuff could be a complete mess which will fall apart tomorrow. This applies to programming, construction, plumbing, managing a financial portfolio, anything. Unless you're an expert, you really can't judge someone's work on anything other than a very superficial level.