Oh no no, we can still do cheap snapshots. We’re not giving up on that. What we’re giving up is knowing exactly when the last reference to one of those snapshots disappears. The garbage collection process we have will clean it up, but not right at the soonest point that it could. That’s the tradeoff.
To make an analogy to programming language design, our change here is like changing from a reference counting or precise garbage collection strategy to a conservative or best effort mark and sweep.