Why tokio::sync::notify use Ordering::SeqCst ?

[bigdogs]

Hi,

I'm reading the book for learning atomic: (https://marabos.nl/atomics/memory-ordering.html)
which says Ordering::SeqCst is almost never necessary in practice

But Ordering::SeqCst is used everywhere in notify， Is there any special reason for that? (or why Aqcuire/Release pair is not enough)