1. Aliasing/abstraction of IP addresses. Being able to change physical location or server of a service without reconfiguring everything.
2. Mnemonics for getting to a particular server.
3. Indicator that a server belongs to a particular organization or company.
4. Grouping services together so they can share resources (like cookies).
DNS solves all of those problems, but not particularly well.
#1: You need to deal with a lot of BS when all you need is stable identifier.
#2: There is a lot of contention around domain names. Users prefer to use search instead of typing long domains. There is no particular reason why my mnemonics should be the same as for everyone else.
#3: Similar-looking domain names used for phishing. Users don't understand DNS hierarchy. Expiration. Hijacking. A tree structure isn't enough anymore. And so on. This one is particularly bad. Like you said, it's not just a technical problem.
#4: Just look at HTTP security headers and all the iframe issues.
The problem #3 can be solved separately from the rest. The rest are relatively simple technical problems if you consider them in isolation and we could solve them much better than DNS does.
That mostly solves technical problems, but technical problems are (probably) not what is driving this effort. Is a user supposed to know that d6998147-a7a2-485a-ac5f-74dddebfe070 is legimately Steam, but d69a2b76-96ca-4d7e-b25c-c5a69848e070 is not? Who verifies the metadata for accuracy? Who says you can't register Bank Of Ａmerica? Those problems, and the other problems like them, are the hard problems, not cryptographically signing the answers to those hard problems. Crypto is easy by comparison.