Unless we are talking about very long numbers, surely the numbers are easier for people to deal with, say over the phone, etc?

I was going to say it's for very long numbers, but I tried an example, and 123645634 becomes ARsz1pHw789c7ESzhy. The output is actually longer, and more complicated.

Looks like it uses a hash. I was expecting it to just convert the base except with something to skip profanity, which would give you something much shorter going base 10 to base ~36. Tbh I don't see why it's like this.