A consulate overseas is more equipped to vet someone from the country where it is located than a USCIS office in New Hampshire. E.g. it has people able to read the documents in the local language and access to the officials who can validate those, it has people able to call or mail local authorities to ask about an applicant's involvement in crime, it has people who can recognize affiliations with local extremist groups etc.

It is actually really bizarre that the USCIS would essentially take the applicant's word without any vetting before this memo.