Priestcraft is commonly seen for this, by analogy, particularly when done by preventing the spread of knowledge, obfuscation or the creation of mystery.
Wiktionary has this excellent example:
Horace (Horatio) Smith, Address to a Mummy:
Perhaps thou wert a priest,--if so, my struggles
Are vain, for priestcraft never owns its juggles.
According to Websters 1913 dirctionary:
Priestly policy; the policy of a priesthood; esp., in an ill sense,
fraud or imposition in religious concerns; management by priests to
gain wealth and power by working upon the religious motives or
credulity of others
Priestcraft as a generic term for expert's practice:
One of the most enduring and troublesome mysteries in economics is
money: how it is created, what sorts of institutions initiate the
process, what kinds of mystique and priestcraft central bankers use in
managing monetary systems, and what rules, laws, or customs limit
Less generic, but showing the analogy:
Working class radicals rallied to the cause, linking
“King-craft, Priest-craft, Lawyer-craft and Doctor-craft” as the four great
evils of the time.
Wordnik has numerous examples, mostly referring to priests.