I mean, no? Why on earth would I want Thursday the twenty thirds mDAU from a year and a half ago? If it's not bringing value, it's costing money, and it's unlikely to provide value, so why keep it?
Heck, not only “what happens on Twitter each day of the week” is a very valid data question, but even by the hour.
However, saving user identifiable information > 90d is a challenge these days - you have to anonymize it, which defeats Musk's purported goal. (And it might be illegal to share that data w/ a 3rd party.)