Pure focused cruelty, or complete incompetence.
You know they've got at least 10x the server cost being wasted by old emails and stuff like that which could be more sensibly purged instead of customer reference documents.
Perhaps it's an anti-recycling effort against those who would otherwise keep running these old processors which once played a respectable key part in Intel's progress.
After digital files first became available for electronic components, there has never been any good excuse for them to go out-of-print after that.