dave2008
Legend
CR is for determining which monsters are stronger than other monsters. There are exceptions, but in general it is really good for that.Right. Currently CR is useless for figuring out what challenges a group. It might as well not even be there.
One number, CR, cannot be the same thing for every group. The same monster can be a TPK to one group and Medium fight to another. It is not possible to make single number do all of that work.
Please note, in the above I am specifically talking about 5e.