Project failures which result from:
Succeeding when everyone else fails is nice, but failing when everyone else succeeds is fatal.
Is it? When everyone is using technology X, it is ok to fail if you use technology X, but fatal if you had used technology Y instead.
It's fatal to technology Y, so the answer is yes.
Because of the way we defined 'failing', it goes without saying that it is 'unacceptable'. You may quibble with that, pointing out that failures beget new efforts, discoveries, paradigm shifts, et cetera, and so they should be accepted. Point taken. Still, the construct of 'unacceptable ... failing' is a redundance we don't need.
The opening remarks above make more of a statement about conformity than about succeeding and failing, being acceptable or unacceptable.
See also: FailureOrientedApproach, AnAcceptableWayOfFailing