Sorry, still not following. I wrote not E2E encrypted. I'm struggling to understand why messages that are not E2E encrypted would require key management.
Yes, you could symmetrically encrypt the tiny portion of personal data that needs to be read solely by you without much added complexity.
However, with few exceptions (password managers, backups, personal notes, etc), the whole point of uploading data to an online service is to allow it to be shared with other people or services. Once that happens, you need all those complicated key management and security systems I just talked about. It's effectively end-to-end encryption.
Yes, you could symmetrically encrypt the tiny portion of personal data that needs to be read solely by you without much added complexity.
However, with few exceptions (password managers, backups, personal notes, etc), the whole point of uploading data to an online service is to allow it to be shared with other people or services. Once that happens, you need all those complicated key management and security systems I just talked about. It's effectively end-to-end encryption.