Because a file (or computer memory in general) is a linear (1D) storage medium and tabular (2D) data is not well suited to linear serialisation. You can't avoid

Because a file (or computer memory in general) is a linear (1D) storage medium and tabular (2D) data is not well suited to linear serialisation. You can't avoid adding complexity (i.e. making trade-offs) to the format and any code that deals with it.