More control on the machine. For example you may want to use certain CPU instructions, or as you mentioned you can eliminate a lot of overhead in certain cases.

More control on the machine. For example you may want to use certain CPU instructions, or as you mentioned you can eliminate a lot of overhead in certain cases. Look at it like melting your own metal piece. Sometimes the screws that you find in the shop are not the exact shape you need and it's better to build your own. I bet most of the things you code with Nasm are not entire binaries. You can write functions entirely in assembly and link the compiled outputs to any binary file once you know the calling convention