I didn't initally understand this from your summary, so trying to rephrase it a bit to how I understand it after glancing over the paper: The paper's thesis is

I didn't initally understand this from your summary, so trying to rephrase it a bit to how I understand it after glancing over the paper: The paper's thesis is that most (?) currently claimed advances in fuzzing algorithms were not proven correctly enough (a.k.a. "in a statically rigorous/significant way") to actually be advances. Meaning, they may well have been just random fluctuations. Then, the paper proposes how to correctly compare fuzzers, and what the community needs to be able to do that (e.g. an agreed upon common body of codebases to be fuzzed, a set of known fuzzable bugs in those codebases, minimum fuzzing time, etc.)