Because we're not talking about a memo posted by one random engineer that got the reaction it deserved for declaring a large fraction of his co-workers sub-standard engineers (among the myriad broken things in that memo). That would have been a story for all of five minutes.
Instead, we're talking about how a large fraction of a major tech company quickly and enthusiastically endorsed it and circulated it.
"Hey, finally someone says it ought to be OK for me to denigrate my co-workers, treat them as sub-standard engineers and sub-standard humans, and propagate junk science to prop up my prejudice! I feel validated!"
That this is even remotely a popular sentiment, rather than something that gets you treated like you just said "the earth is flat", is the story here.