Nice idea but (according to the article) that's not how it works:
> Under the system, users can input these seven-digit codes on online shopping websites, and their addresses will automatically appear on the sites.
So the sites still use the physical address. In fact, the postal service itself doesn't even use the code.
The purpose is to simplify form input on websites, which was already solved by browser autocomplete.
Browser autocomplete works Really Badly for Japanese addresses (no standardized way of inputting addresses, including which font to use), so it should solve one major problem in Japan. That's different from e.g. my home country. Or almost anywhere else, for that matter.
TIL, I didn't know the situation was particularly bad in Japan.
I suppose the 'digital address' is solving the problem by effectively standardizing the input format.