Technically correct but in practice the FBI does actually write and repeal laws in 2 incredibly important ways that I constantly see people forget about.
First every law enforcement body in this country has to prioritize which laws it wants to enforce, to many laws on the books to do otherwise. By prioritizing some crimes over others, they change the nature of the law itself, at least insofar as it impacts the lives of regular people. A law is not a really a law if its not enforced (just like a right is not really a right if it does not protect you in practice).
Second, and even more directly, the FBI in particular has a massive political influence in congress over which bills are written and which bills die and which bills get passed. Its difficult to overstate how powerful the law enforcement lobby is in this country, and a big part of that big tent is the FBI.