That is a problem of interpretation by amateurs more than a problem with the test itself. Myers-Briggs gives you PERCENTAGES of every trait, then it uses 4 letter labels to make things simpler for people, but you are supposed to understand that a person that scored 49% introvert in the introvert-extrovert spectrum is going to be far similar to a person that scored extrovert with 51% than to a person that scored introvert 10% because its a spectrum not an absolute value.
That is the reason that modern tests like Big Five did away with the labels, because people were incapable to reason beyond them and kept making dumb assumptions like "He scored introvert so he must hate parties or I scored introvert the first time but extrovert the second (a potential 1% difference between the labels without the percentages associated to them) so the test is crap".