It's been a nice kind of fig leaf, but constitutionally the president is the AG's boss, so it doesn't make any sense for the AG to investigate the president. There's an entire branch of government given this power in the Constitution, they've just decided they don't want it.
Exactly. Congress doesn’t want any of their duties. War declaration? Nah, let the President do it and call it “not a war.” Budget? Well, technically we’ll appropriate funds, but we’ll only do a big CR once in a while. Tariff policy? Nah, let the President do it all with the “national security” loophole, no matter how absurd. Impeachment and removal? Well, not when it’s your party’s guy.
For all the hate Trump gets, it’s Congress who’s created and who props up this monarchy.