So assuming Levels.fyi is accurate (their numbers are $20k more than salary.com which is more accurate in my opinion): my point was that I am average, right in the middle. But this article is telling me (and by extension, since I am at the mean, 50% of software engineers) are extremely underpaid.
And maybe on a nation wide scale that includes non-Boston metros, I am. But for Boston... I'm not over or under. I'm right in the middle.
Basically based on my research I think this article is for a very niche group at the top 25% of pay ranges and is not accurate or relevant to 75%+ of software developers (numbers are ballpark).