True that, they did increase the book size and yet it's till below the dict size:
compresses and decompresses a 2399KB HTML ebook using the LZMA compression algorithm with a dictionary size of 2048KB.
Doing the test below 4MB of L3 would hurt, doing with with less than 2MB would decimate the test.
I agree these benchmarks have issues, but there's a consistent trend (eg. AnandTech's SPEC results are similar—they use active cooling to avoid the question about thermals) and the most reliable benchmarks, like compilers, aren't outliers.