You can find an exception to any rule, but you'll find, in general, that its both self-evident and unsurprising that make is on the decline, and being replaced by other tools.

plan9 exists in an enviable position of only needing to build in a few controlled environments.

For example, http://9p.io/sources/plan9/sys/src/libmach/mkfile reads:

    CFLAGS=$CFLAGS -I/sys/src/cmd

Cute. Non-portable. A perfect example of how make is useful in trivial or contrived circumstances only.

/shrug

Try reading the llama.cpp makefile, which is an example of an excellent cross platform makefile that works very well: https://github.com/ggerganov/llama.cpp/blob/master/Makefile

^ this is what many real Makefiles look like, and this one is excellent and well maintained.

Many are worse.

Make is good when you only have easy problems to solve (like, specifically, only having to build one specific constrained environment for one specific compiler).

Woah, what is that @{ construct in that mkfile? I cannot find it in the GNU Make Manual (https://www.gnu.org/software/make/manual/make.html). I use backslash-before-newline for multi-line loops like that.