Another reason is that by providing an identifier for this string literal, misspellings of it can be detected by the compiler whereas there is nothing tying separate string literals together.
Similar to how linters stop you from overthinking indentation in specific cases, or some naming standards, and later rename/reformat-wars.
That's what leads to dogmatic cargo-culting. Good software is written by thinking about the circumstances and doing what makes the most sense, not by mindless rule-following that don't always make sense.
I don't know why someone would be so worried about typos and introduce more verbosity and redundancy in the process; but then again, I don't use an IDE and I've never had this problem.
Good software may mean thinking about circumstances like "we're dealing with lots of text parsing and have seen bugs from typos in common keywords" and doing what makes most sense: "let's prevent those in the future, but using constants for keywords". It's only cargo culting if you don't know why you're doing something.
Setting a rule so you don't have to debate something later is a valid solution and may still offset some redundancies introduced this way.