In the GNU toolchain world that sees a lot of embedded use nowadays, it's pretty common for the preprocessor to be used for assembly files. A file named with a capital .S suffix is preprocessed.

You might think that the preprocessor is "weak", which it is, but, look, I used it to define a loop language for Awk, with not only a variety of standard clauses but an easy way to write new clauses.

You can loop over strings, associative arrays, ranges, find maxima, minima, argmax, count, collect lists (there is a Lisp-like layer defining cons cells) and such.

https://www.kylheku.com/cgit/cppawk/about/

(See the info about <iter.h>. There is a man page covering the loop macro and the test suite has coverage of all its clauses in testcases-iter).

They were never a thing in the UNIX world, which is where most stuff nowadays comes from.

Such Macro-Assemblers are also quite common on the mainframe world, besides the 16 bit home micros.

In any case, nasm and yasm do exist as FOSS version of such ideas.

Why is it suprising? There is no real need for people writing hand tuned assembly any more. And great optimized assembly code can work like crap on next gen of chip. Why bother?