Why does most of the chromium based browser so ungrateful to them. Vivaldi doesn't mention Chromium in the homepage even once but has "Chrome vs Vivaldi" compar

Why does most of the chromium based browser so ungrateful to them. Vivaldi doesn't mention Chromium in the homepage even once but has "Chrome vs Vivaldi" comparison in the homepage. At least they should mention it, and better contribute back to it, if the 99.9% of your product is based on open source project.