Agreed. In fact, code can be more expressive than mathematical notation, and providing code would do a better job of demonstrating a theory.
A lot of the proofs are just to legitimize papers. The cynic in me also thinks that by not providing code, the authors intentionally make it more difficult to reproduce results to hide tampered data. You see the same happen in science all the time with p-hacking, or with just plain fraudulent data that is purposely difficult to reproduce.
Luckily there are a good number of papers that provide a repo link, but not enough yet.
A lot of the proofs are just to legitimize papers. The cynic in me also thinks that by not providing code, the authors intentionally make it more difficult to reproduce results to hide tampered data. You see the same happen in science all the time with p-hacking, or with just plain fraudulent data that is purposely difficult to reproduce.
Luckily there are a good number of papers that provide a repo link, but not enough yet.