Pact generalizes the versioned key-value database to be key-row, maintains a full history, and the rest of the language allows you to enforce whatever invariants you want, with whatever key-based authorization scheme you need.

As such, Pact is really a very simple language, which is really important for business adoption. If people are going to be entrusting code to execute contracts, you have to be able to read that code with some hope of understanding what it means. This is also why Pact is interpreted, not compiled: that way you can easily see what code is stored in the ledger.