The main assumption you are making here is that these career bureaucrats are not at all partisan, which is a pretty bold assumption to make. I'd like to see some evidence that this is true. That aside, if Congress isn't delegating something to the executive that's their fault. Write better laws. These people are mostly lawyers anyway. What, they forgot how to do it on the campaign trail?
Yes, the rulebooks are literally rewritten every 4-8 years. EPA examples, Trump renewed the permit for the Keystone XL pipeline (Obama had denied it), 'rewrote key rules curbing U.S. carbon emissions and other environmental regulations' (1), rolled back all of the Obama administration's fuel economy & emission standards, rolled back efficient lighting regulations, etc. He replaced the Clean Power Plan, redefined what species are endangered, weakened the Coal Ash rule, revised the Mercury standards. And so on.
He did all of these directly through the EPA- not by passing new laws. Then, Biden reversed all of these
1. https://en.wikipedia.org/wiki/Environmental_policy_of_the_Do...
I mean, that's how it used to work:
https://en.wikipedia.org/wiki/Pendleton_Civil_Service_Reform...
Of course, that's the short term "republican makes it into office" solution. Past that, to other presidents, I don't know. In my personal opinion, I think they're banking on never having to get there.
I think their logic is basically "these people function ~identically to if they were democratic political appointees, so we might as well get the benefits of them being political appointees when we're in office". Whether that's actually accurate can be debated, but it's not just "let's not worry about ever losing ever again".
https://www.semafor.com/article/07/05/2024/trump-disavows-pr...