I'm in agreement with the consensus that date area has been restored via a chemical treatment ...
In that regard it loses some numismatic value ... but the true value depends on the owner views of collecting objective ... not our opinions/values of such coins.
There was a thread here on the CCF many years ago (I don't know how to find it) where the collector was inspired to acquire the entire
Buffalo nickel series at a ridiculous low cost per coin ... something like 50 cents per coin average cost.
He made tremendous progress ... and we cheered him on ... there were plenty of 'restored dates' in that set ... but none of us cared because this particular collector was
enjoying the hobby in his way.
The most tremendous lessons all of us can gain from participation in this best of internet coins forums ... IMHO ... are education and decide what suits you based on that education.
Do what suits you with this 1916-D Buffalo ... you have now made another step towards 'education'
David