Given a number of reasons we can imagine WHY someone would shoulder a new name in part or in whole, we have to consider
1) hiding from law enforcement,
2) changing back from a name given at adoption to the original parental surname as an adult after it is discovered and takes it on,
3) an illegitimate child as an adult discovers the bio parental surname and takes it on (saw that recently in blood kin),
4) one of the constraints of an inheritance is that the name must be changed from abc to lmn or no inheritance (saw that twice in Old Virginia records)
5) man or woman "went out for a newspaper" one day and just decided to keep going and took on a new name
6) the mother (usually the case) remarried and the child uses as an adult the surname of the step-father, usually because it lacks any acquaintance with or any affection for the absent bio father
7) someone classed as "mentally unstable" by the people around them change their name from "Roger Farnsworth Hapgood" to "Super Bambam Hapgood" and if they can convince the court (with a well paid and very competent lawyer at their side) the court will grant the change
8) sometimes the name at birth is a social impediment such as the sisters Ura Hogg and Ima Hogg, or "Ronald Fuchs"
and I'm sure, Milton, you can come up with some other causes for changing a name
AS TO WHETHER some genealogist was playing games they should not wear the badge of "Genealogist" and further, if they did not document the change of name with some paper work, you might want to cherish some doubt about this matter. Or you can root around in some archives somewhere and find what you can