Decades of experience have shown us the massive costs of doing so - the crippled velocity and soul crushing agony of dba change control teams, the overhead salary of database priests, the arcane performance nightmares, the nuclear blast radius, the fundamental organizational counter-incentives of a shared resource .
Why on earth would we choose to pay those terrible prices in this day and age, when infrastructure is code, managed databases are everywhere and every team can have their own thing. You didn’t have a choice previously, now you do.