It’s not a misuse if the word at all, digital means that information is processed as a sequence of digits, e.g. 0 and 1 if using binary, but any set of digits in any other encoding scheme would also be valid.
Modern computers are all digital computers, so it is exactly the correct word to use.
It is not correct because it is ubiquitous, through widespread use of an misnomer, but because it was explicitly defined that way.
