Comment by giantrobot

The issue is less COBOL the language and more the literal business logic the COBOL is encoding. You can learn the COBOL language as easily as any other. What you can't learn as easily are the accounting rules, administration policies, and regulations any major COBOL codebase is implementing.

You'll be able to see the code multiplying a dollar value by 0.03 but not necessarily know that this is because of some statutory requirement of some Minnesota tax code that only applies to industries producing both left and right handed monkey wrenches but only if the company was incorporated before 1975. That obscure law isn't referenced in any documentation but was found by an accountant in 1982. The change was made to the code but only referenced in a paper memo with a small distribution list but all of those memos were shredded after being archived for ten years.

ChatGPT can't really help document code that's decades old and doesn't have any references to the why of the code. The how is straightforward but rarely as important as the why.