First, why? Basically, all of the classic drivers are in maintanence
mode (even i965). Second, many of them rely on code that no one works
on, and very few people still understand. There is no CI for most of
them, and the Intel CI is not integrated with gitlab, so it's easy to
unintentionally break them, and this breakage usually isn't noticed
until just before or just after a release. 21.0 was held up (in small
part, also me just getting behind) because of such breakages.