When solutions to a problem are said not to be right because they are not perfect
"If we go on the Highway 95 at four in the morning we will get to our destination exactly on time because there will be NO traffic whatsoever" By creating a false dichotomy that presents one choice which is advantageous - while at the same time being completely implausible - a person using the nirvana fallacy can attack an opposing idea because it is imperfect. The choice is not between real world solutions and utopia; it is, rather, a choice between one realistic possibility and another which is merely better.
Perfection is a human judgement. It does not map directly to a physical world object or property. You can only find perfection in the abstract world. Therefore this fallacy is a means to reject physical world evidence. One way to deal with it is to show that even the most useful scientific theories are not perfect but that it would be irractional to reject them completely and by implication substitute a worst theory because they still have limitations.