Often the legacy of an engineer (or team) who "did what they had to do" to meet a deadline, and if they wanted to migrate to something better post-launch, weren't allowed to allocate time to go back and do so.
At least JSON or CSV is better than the ad hoc homegrown formats you found at medium-sized companies that came out of the 90's and 00's.
At least JSON or CSV is better than the ad hoc homegrown formats you found at medium-sized companies that came out of the 90's and 00's.