It is technologically possible to fine tune models to each user's taste but it is costly. Nowadays decent performance comes with 70B models and those would require 140GB GPU. Like $17k computers per person. Not very feasible. And it takes lots of time to train them.
Currently, "system messages" i.e. the first message in a session that describes the assistant (the role of the LLM in the conversation) is more suitable to achieve this. Person A can say "You are the woke assistant that will recommend me the best artists in the world" and Person B can say "Please dont include the most popular artists because they are mainstream and I hate mainstream". Then the LLM will act accordingly.
It is also possible to "instruct" in every message. Like "pretend that you are a great recommendation engine for Jazz and give me some recommendations considering I like these artists".
Using RLHF techniques models and humans will have a symbiotic relationship imo in the future. I mean the concscious humans need to think about raising and training the best AI and dont leave the playground to evil actors..