This wont work if:
v2: contains a mandatory field (depreacted)
v3: contains field not more
If my app only publish latests (v3)
The converter app is unable to add the deprecated field.
It is a fixed requirement to support deprecated apis for at least 6 month to let consumers enough time to migrate.
Always publish the oldest supported version will also not work in case if V3 add a new field.
Because the business force us to publish the new field asap not only in 6 month