If I recall correctly one hurdle for customized medications is the licensing process. Licensing and FDA approving a new medicine is costly. That's one of the reasons bacteriophages are not used nowadays, besides a few exclusions. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6521264/)
Thank you for sharing that link. I always wondered why phage therapy isn't more widely developed. This feels like an example of an exponential tech improvement that our linear democratic institutions are having trouble adapting to. I wonder what the answer will be.