Why would I want to bind OracleCommand parameters by position?
You might want to do bind by position if you wanted to bind different values/parameters to two or more binds that were given the same name.
Although I can't explain why you as the developer would name the binds the same if you didn't want to bind the same parameters to them.
Most likely this is due to legacy functionality where named binds didn't exist in previous versions of OracleCommand, and when named binds were introduced the default was to use positional binding to prevent breakage of legacy code.