Comment by jug

This is a nice clarification story why there was no HLT in the idle loop of Win95/98, but it doesn't really explain why there wasn't an option to enable HTL as an advanced feature by modifying the registry. This is especially true if the HTL-related freezes were mostly a laptop problem. There were many strange options to customize Win9X by altering values in the registry, but not this one.

I don't understand why you wouldn't have a hardware whitelist, and a way for new hardware to opt in.

Like most stories from Raymond there is quite a lot of exaggeration. I really cannot imagine any hardware that would "lock itself unrecoverably" after running a HLT, mostly because such hardware would have burn even harder if you disabled interrupts and entered a infinite loop, which would have been likely an almost once per year event for most users running random programs.

In addition, MS was quite happy to ship advanced but dangerous features to customers only hidden behind user-accessible plain checkboxes. One example that comes to mind is the "DMA" checkbox in the IDE controller settings page. Guaranteed to corrupt your data and render your system unbootable on certain hardware (likely a worse scenario than anything HLT could potentially do to you), and at most you get a warning box claiming this may happen when you enable the checkbox.

Most likely, MS knew it was trivial (due to the design of DOS-based 9x/ME) for a 3rd party to ship either a utility or even a BIOS addition to do HLT-on-idle (and in fact, most laptops would do so in their APM BIOSes), so the problem didn't appear to them to be significant at all (and, frankly, really wasn't a significant problem at all). Not so much for e.g. DMA which would require a new driver replacement.