The drive for a world government and totalitarianism are the largest examples. There are positions which require a degree of control over something, and domination is the result. It takes the form of purifying. Dominators become purifiers when controlling something. The purifying is nothing but domination, it doesn't really purify.
Some examples show how it works.
Editors and reviewers supposedly purify science by stripping out rationality, which they call speculation, and redesigning someone else's research, which they know nothing about. To leave their indelible mark on someone else's work, they redesign sentences, reversing subject and predicate and soforth making the author look like an idiot. Another example is removing spam from search engines. The spam removers spend their lives developing rules, and they all have different rules. To follow the wrong rules is to spam.