Larger stacks is a larger buffer.
Just as the network can only have a relatively small amount of traffic actually "in flight" but lots can be stuck in buffers - so likewise only a relatively modest amount of containers can be on ships in the ocean.
You need a buffer or every little inconsistency reverberates and it gets out of hand, but bufferbloat shows how too much buffering makes things worse not better. If your metrics say (and some trivial metrics do) that the huge buffer is better, your actual experience contradicts that as everything feels like you're wading through molasses.
I don't have any relevant expertise to judge what the right metrics are for international shipping, but it certainly raised my eyebrows that "Let's make the buffer bigger" is seen as automatically a good idea.
Of course, a network buffer is very different from a container port's stacks, maybe this genuinely is going to make a huge difference. I think more likely it turns out to make no real difference, but can be portrayed as a genius idea that just wasn't embraced wholeheartedly enough to be effective.