Probably that's why Google is trying to improve network protocols (QUIC, HTTP/3) rather than relying on one-off optimizations described in the article.
How does QUIC or HTTP/3 change things? Polling is polling, regardless of whether it's over HTTP/1, HTTP/2 or HTTP/3 (QUIC).
It still optimizes overall network efficiency much more than enough to negate 0.001% inefficient cases using polling? I would say this is a right prioritization of optimization engineer headcounts, which is pretty scarce.