That’s a fair point. To be fair to the academic definitions, “eventually consistent” is a quiescent state in most definitions, and there are more specific ones (like “bounded staleness”, or “monotonic prefix”) that are meaningful to clients of the system.

But I agree with you in general - the dynamic nature of systems means, in my mind, that you need to use client-side guarantees, rather than state guarantees, to reason about this stuff in general. State guarantees are nicer to prove and work with formally (see Adya, for example) while client side guarantees are trickier and feel less fulfilling formally (see Crooks et al “Seeing is Believing”, or Herlihy and Wing).