If your code may be compiled, to use the Intel x87 numerical coprocessor, an important issue is the so called "excess precision": Different values on chip can collapse after being rounded and stored to their memory locations, invalidating previous comparisons. Spilling can happen unexpectedly. Note that Intel calls the x87 "legacy"
What is "coder arrogance"? The expectation that the 20-year-old API (SSE) will be used over the deprecated 40-year-old API that is currently losing compiler (and silicon) support? Can you point to a running x86 machine today that does not have SSE?
It is also faster and more precise to use double-double for math over x87 extended precision. There is literally no reason to compile an x87 instruction today aside from a programmer not knowing better.
