I'll put the caveat up front: - Apple is the exception to the rule and does swap arch periodically, because they can. But with a migration phase. Which they

I'll put the caveat up front: - Apple is the exception to the rule and does swap arch periodically, because they can. But with a migration phase. Which they generally did ok at. Because users care about software, not PowerPC v x86-64 v ARM. Being "transparent to software" wasn't a goal of adding extensions to x86, for example. Yes it absolutely was, and I can't possibly understand why you'd think otherwise. Can't think of a thing that quit working because SSE showed up (surely there was something, but it was a rounding error). Or AES-NI. And since you mention it, that's a big reason why x86-64 won; it minimized breakage of the software people were already using, as opposed to Itanium. Or the goal of having compilers support RISC-V, for another example. Not sure what this point is making. Compilers support all sorts of oddball archs for various reasons. When RISC-V gets an installed base to speak of outside embedded and hobbies maybe we can make specific judgements. Until then....... Drop-in the new AMD thing and get a speed bump with your current software. Which is all most users care about. Which is why the hardware vendors focus on it. Reap profits immediately from that and if it leads to opportunities for innovation perhaps they'll consider that later. 1) Reaping profits is kinda the point of having a company, and profits will go down if your idea of 'innovation' is 'this new thing we have is SO COOL...you just have to throw out all the stuff that used to run on our stuff'. 2) If you don't call what Intel and AMD are doing to get that 'speed bump' year after year for decades in processing power and power consumption 'innovation'...I don't really know what to tell you. "because software that interacts with our hardware is a dependency for so much, it would not be worthwhile to recompile even if the compiler existed today for free." Software can be recompiled for every new generation, if you want to (and can limit you users to certain generations of processors). Sometimes that makes sense and some people are constantly recompiling to maximize something (e.g. HPC folks). Have you ever looked at the number of compiler switches GCC & LLVM have to optimize for different micro-architectures? Just for x86(-64)? There's a huge continuum from "maximize performance at the expense of limiting hardware support" to "run on the maximum number of machines". Pick your poison.