You are right there is a lot of risk involved in refinancing credit card debt into a mortgage, you point out (as did I several times) the big risk of increasing mortgage debt is risk of default.
The reason someone would consider it is because it could potentially save them hundreds of dollars per month. For some people that might mean the difference between getting through the next 6–12 months financially.
If you're worried about cash flow, all expenses that can be cut should be at least considered.
It’s not an option that makes sense for everyone. But, it is a possibility that can be explored. If it’s explored and then ruled out as an option, that's great.