RNA viruses have a faster mutation rate than DNA viruses.
Chickenpox = DNA virus, Coronavirus = RNA virus.
That Chickenpox is a DNA virus is why, like HIV, it can survive in the body for the long term and re-emerge decades later as shingles. DNA has a double helix which has error-correction and is more stable. However that makes it also physically larger and more complicated. RNA is small, sloppy, and cheap.
Source of all this: Spillover, David Quammen: https://www.amazon.com/Spillover-Animal-Infections-Human-Pan..., it's a good & topical book, a little bleak but good. There's a discussion of exactly this about halfway through the book.
So I do not believe your comment is factually correct. Sadly, the COVID-19 causing virus should have a high potential mutation rate similarly to all RNA viruses.