Primary dealers in treasury auctions
(As requested in comments)
Primary dealers have a privileged position, so there is value in being registered as a primary dealer.
The Treasury or Central Bank can impose standards of behaviour (e.g. an expectation of reasonable participation in all bond auctions or open market operations) as a condition of maintaining that registration. There are rules such as https://www.newyorkfed.org/markets/pridealers_policies.html and you will find sections such as

The New York Fed expects a primary dealer to:

participate consistently as counterparty to the New York Fed in its execution of open market operations to carry out U.S. monetary policy pursuant to the direction of the FOMC;

provide the New York Fed’s trading desk with market commentary and market information and analysis helpful in the formulation and implementation of monetary policy;

participate in all auctions of U.S. government debt; and

make reasonable markets for the New York Fed when it transacts on behalf of its foreign official account holders.


In the selection process, the New York Fed will evaluate a prospective primary dealer with these expectations in mind.

In effect primary dealers provide liquidity and information and markets even at times of crisis, which comes at a cost, one which countries such as the USA think is worth paying to get the increased financial stability it brings.