Frankly, with the inception of modern CMake over a decade ago, the only reason anyone has to stray out of cmake's DSL happy path, comprised of all the tried and true declarative bits, is whether

a) they have to do a very niche/specialized/extremely custom extension to CMake, or

b) they have no idea what they are doing.

More often than not, b) is the case.

You and I discussed exactly this 3 months back. I won't restate my responses here, but for anyone curious: https://news.ycombinator.com/item?id=26722717