Sometimes when I talk to other developers and the topic of a DID comes up — I get the feeling they are making them out to be more complex than they really are
They are just a way to turn an ID (identifier) into a URI
There are certain technologies that expect URIs — and if you want to use your ID with it, you need to turn it into a URI
As a side note — the Fediverse turns Fediverse IDs into URIs by turning them into acct-URIs (rather than DIDs)