Any scheme of a fixed number of human types invites the objection that it produces stereotypes, and it is a fair objection to raise here. Pearson's own answer is that the twelve are not personality types: a person is not one of them but moves through all of them, with different ones active at different periods, and the scheme is offered as a developmental map rather than a classification of people. In practice, and especially in the branding and workshop literature derived from it, the twelve are constantly used as fixed types, and popular online tests assign people to one. That use should be distinguished from what the framework claims. It should also be said plainly that the twelve archetypes have no established psychometric standing: they are not a validated instrument, and there is no body of evidence supporting the twelvefold division as an empirical finding about persons.
The Myers-Briggs comparison is worth pressing further, since it is the closest analogue to what happened with Pearson's twelve. Both trace a lineage back to Jung's 1921 Psychological Types, both were developed by writers working outside academic psychology, and both achieved mass commercial reach, corporate training programmes and online self-assessment tests, far exceeding anything their originating theory or evidentiary base supports; the science journalist Annie Murphy Paul's The Cult of Personality (2004) documents the Myers-Briggs case in detail, and much of her critique, unvalidated categories treated by users as fixed and diagnostic despite their originators' own more modest claims, applies with little modification to the twelve-archetype scheme's popular reception.