What was their original mission?

My sense is that startup mission statements are ~meaningless. Builders try to build great things that lots of other people will find valuable.

Anthropic has one of the best moats of any business that's been created in the last 50 years.

Numerous companies have tried and failed competing with SoTA foundational models. If Anthropic had no moat, Apple and Meta wouldn't be paying them billions for coding asistance.

Meta, Amazon, Apple, and Nvidia would all have SoTA competitors to Claude. They all tried and have not produced a competitor.

Instead you have three companies that stand alone making billions from foundational models.