For purposes of my event workflow, the key difference is that when I apply presets that include noise reduction to hundreds of images and then export finished JPEG’s for delivery to my clients, DxO takes half as long as Adobe.
Denoise is getting more competitive, and it has the unique advantage of working with reduced-rez mRAW and sRAW files. And, as you say, you are a hobbyist. I’m glad that it serves your purposes well. But this does not change the fact that it is 2X slower than DxO, and for high volume professionals this is a significant consideration, which is why I mentioned it earlier. You may not need the speed, but plenty of other people do.