I think you're right, but it's important to emphasize many of these attempts to tell the story of market share get major facts catastrophically wrong. The decline in Firefox market share from like 33% to below 10% is mostly because the world pivoted to mobile, and Firefox "dominance" was in a world of desktop browsers. It was defaults and distribution lock-in as the world pivoted to mobile that led to the change in market share. As well as the web as a whole effectively tripling in number of users, and Google leveraging its search monopoly and pushing out Chromebooks effectively at cost.

For some reason that part of the story always seems to get omitted, which I find bizarre. But the web pivoted to mobile and Google flexed its monopoly powers. I would argue that upwards of 95% of the change in market share is explained by those two factors.