> ...These constraints are structural; engineering effort cannot remove them...

> The trade-off analysis shows that three sync engine vendors converged independently on this conclusion from different starting positions.

This is the big irony. That the vendors all converged on the fact that sync engines only really "work" when you remove the offline part. But, at that point they are a complicated/over engineered cache or worse introducing hard distributed computer science problems unnecessarily.

For me the problem is that in practice it only fits really well with quite a specific subset of problems, but we desperately want it to be a general solution that can apply to all the things (or at least it's often marketed that way).