The point is, many people - even here, on HN - didn't read the full memo themselves. Instead, many of them depend on summaries from journalists (or, should I say, clickabiters), grossly representing the original document. Honestly, when you read articles like "Shocking quotes from the anti-diversity manifesto", I perfectly understand why some people decide they have absolutely no intention to read the whole thing. And I'm not sure the blame is completely on them.
> Do you assume that the people who disagree with the memo don't have the capacity or will to read through a mere 10 pages?
No, I assume that people making completely unfounded claims about the contents of the memo (we've seen them in every single thread about it) have not read the memo.