How has no one solved memory yet?

I get that there a lot of challenges with memory such as selective retrieval and loss of detail etc. but how has no one come up with a solid solution? Is it not one of the most important aspects of AI and agents proper context management and. therefore. memory for cost and speed and long term usage? I feel like all 'memory' I see is just bolted onto system prompt or basic RAG and not a properly thought out system but I can't figure out why no one seems to be taking this that seriously submitted by /u/MontyOW [link] [comments.