At best those amazeballs advantages are applicable only at Google's scale, and have very little impact anywhere else.
Worse, still,
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We find that over fast Internet, the UDP+QUIC+HTTP/3 stack suffers a data rate reduction of up to 45.2% compared to the TCP+TLS+HTTP/2 counterpart. Moreover, the performance gap between QUIC and HTTP/2 grows as the underlying bandwidth increases.
https://arxiv.org/abs/2310.09423
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And if you believe the discussion here https://news.ycombinator.com/item?id=25970258 it increased the load on the server unless you can "spend years optimizing it".