HLL's save time. The early programmers are the ones who made the HLLs The had all the ASM the wanted. But they said this does not cut it. Keil on an 8052 does not bring you down to 30% overall. It will never be as fast as tweaked ASM. But how often does it need to be? They can be mixed so the ASM can be used as needed.

100% asm depends on having a whole lot of old stuff to grab from (not that HLLs do not). The time saved is big. Add in something like TCP/IP or floating point the HLL wins.
My first real project was a project done in asm with floating point. I converted it to C for practice. The costomer wanted to add something. My boss that the time used my code rather than spend another few weeks with ASM and floats.

The bigger the project the better HLLs look.
(with a PIC16 C always looks good)