HTTP/2 uses compressed headers (this was often considered a problem with HTTP/2 by detractors because the headers are a compressed binary block that need to be decompressed and decoded to be read) and the benefits of smarter item caching still mostly outweigh concatenation in HTTP/2.

This same also applies to the author's own Caveat section (that large concatenated files compress better than a collection small files) because the entire stream is compressed roughly in the same single compression stream, which while not as well optimized as the case where the compression has access to optimize a single full file, should adapt better to give better performance with lots of individual files in the stream than compressing them all directly as individual files.