The myth that the original Mackintosh was not intended to have a graphic display with a pointing device is debunked in TFA.

The only technical detail that we know about the original Mackintosh that was a mistake was the choice of the MC6809 CPU, for reduced costs.

MC6809 was a very nice CPU and for many programs the Intel 8088 CPU from the IBM PC was slower than a 2 MHz MC6809, but MC6809 was limited to 64 kB of memory, so the original Mackintosh would have become obsolete very quickly.

This is not enough to allow anyone to claim that it would have been a commercial disaster, but it would certainly would have had a short lifetime and then there would have been significant costs to port any software to a replacement CPU with a greater address space.