The president can type up all the proclamations he wants. Some things he can do. Lots of things he can't. Re-writing law on the fly from his office isn't one of them. If changing laws to suit the whims of the president were simply a matter of signing a typed out document in front of cameras, congress would have been out on the streets looking for employment centuries ago.
So when trumpity trump trump drags the photographer and a few suits into the office to sign off on another one of his paper tweets - er executive orders, to proclaim how he's just done something like eliminate laws or increase the size of the military or fired the EPA, he's wasting paper. No matter the bluster and pomp of the bullshit, this county is not and never has been run by executive orders. The congress, the courts, the states are all partners and they don't have to go along with the trumpity trump trump.
Congress passes the law. The Courts interpret the law. The executive branch enforces the interpretation. It's not one guy making statements and singing papers.
He wants you to THINK he's doing this stuff because it plays well to his base, and is way easier than actually doing some thing.