In article t, "Bill Sohl"
writes:

It may have been increased for that purpose, but it was not originally
implemented for that purpose.

Fair statement.

The "original" morse requirement was to
enable non-amateur stations to dialog via morse with
amateur stations in case of interfereing operation.

That was one reason. Here are some others:

- To permit amateur stations to dialog via morse with each other
- To set a minimum standard of operator qualification so that newcomers would
not try to learn the code on the air. (Remember that in the early days the
effective selectivity of radio systems was not very good)
- To support hte idea of the amateur service as a training ground for
commercial and military operators
- To support the use of the most spectrum-efficient mode then available

The increase to 13wpm was, as the article states, intended
to raise the bar of entrance criteria to limit the number
of new hams.

And so was the simultaneous upgrading of the written tests.

73 de Jim, N2EY