Washington Post article enumerates in concrete terms the post-Watergate guardrails that are under attack, including:

• 10-year term for FBI directors created in 1976: (“Trump has forced out two FBI directors.”).
• “The Impoundment Control Act of 1974 aimed to prevent presidents from dismantling agencies.”
• A system of independent inspectors general in government offices established in 1978: (“Trump has fired many of them and is seeking to replace them with loyalists.”).

As the article notes, conservatives see these reforms as an unconstitutional usurpation by Congress. However, one could argue that they were the system of checks and balances at work, and most of the problems we see today are the product of the absence of checks and balances.