The macros! Wtf were they doing with the macros! They didn't want to have a normal assembler that kept people writing maintainable assembly code. They just had macro stacked on macros (my memory here is literally 30 years old, I had to write windows 3.1 vxd drivers) and it didn't help, because they had to use the same registers you were using to do their work. An obtrusive non-abstraction that made life painful.