The key to x86 assembler/machine code was avoiding the software interupts as they were painfully slow. Sure, when you are dealing with a 512byte boot sector you are better of offloading as much code as you can to software interupts, but for everything else the battle was to come up with something faster than the software interupts.

In many cases some basic routines used in qbasic was actually faster than their counterparty interupts in asm. A grand example of this would be using mode 13h (320x200) and interupt 10 to set all pixels on a screen to a single color, which could take up to 2 seconds using machine code and bios interupts (as it verifies vertical and horizontal refresh prior to setting the pixel). Using interupts however is relativly painfree as the author pointed out.