[catnaroek]

> In the worst case everything ends up being tightly bound (...)

Your tradeoff is between “tightly bound by shared data structures” vs. “tightly bound by process synchronization”. I don't see how either is better than the other.

> the real world is rarely so kind

In the real world, from what I've seen, while everything is interconnected to everything else, not all the connections are equally strong or important. If you want to compute exact results, without possibility of failure, no matter what the computational cost, then sure, you need to take all the connections into account. If you can trade some accuracy for performance gains in the average case, you'll probably want to find ways to prevent minor failures from bringing down the entire system.