PLEASE make your code platform-specific!
To be honest, this sounds more like Intel saying "PLEASE, make your software platform-specific! Load it up with processor-specific instructions." To be honest, of course, if ffmpeg, x265, etc. did not have any of that code in it, they would be dead slow. There are specialized cases (video encoding being one) where you'll get MASSIVE speedups from using these types of instructions. But, in most cases, I'd really prefer the compiler to take care of that and leave my code fully portable.
I may just be being cynical, this may just be a matter of Intel genuinely wanting to point out cases where spending a few minutes adding a CPU intrinsic, or replacing you rmath lib with Intels, or the like, will get you your speedups, rather than losing sales to ARM or POWER or RISCV or whatever where a possibly already optimized copy of the code outruns (or out performance-per-watts) the Intel system.
Either way, I do take it as a good sign in so far that Intel is seeing enough competition to find this necessary. Healthy competition really makes things more interesting (especially as a Linux user where besides supporting the x86/x86-64, it suports MIPS, ARM, POWER, RISCv, etc. etc., so there's a reasonable chance of having a distro already up and running on whatever interesting hardware comes out.)