Note that I specifically didn't say that the % tells you if the amount actually is life changing, just that it tells you whether the founders are serious about giving early employees a shot at such an outcome.
The signal is about the founders themselves, which is an important consideration when joining a startup.
Number of shares and current strike price + latest valuation, along with any practices for minimising tax burden, are still hugely important pieces of information. My point was simply that even just the percentage tells you something about whether it's a good company to join.
% needs context of how many other employees there are and what the valuation is a grant time.