You can hardly blame anyone for mistakenly attributing the feature to Mozilla. Until not too long ago, you had to either pay for the browser or view crass and ridiculous advertisements to use the browser. The percentages the Big O was showing on traffic statistics were so small, they could be labeled miniscule. The exposure to the browser was slight, to say the least.
We could change it to say something like "Mozilla was the first to provide tabs in a browser you didn't have to pay for and without ads."