Eich was CEO from March 24 to April 3 of the same year. I highly doubt that was much of the problem.
Certainly losing his technical talent is likely to have contributed to the problems, but I suspect it's 100x more of Chrome's dominance and Mozilla's reliance on Google's search engine contracts for revenue.
After leaving Mozilla, he went to Brave, where they launched a privacy-focused browser which inserts affiliate codes when users visit certain websites, and which collects donations "on behalf of" content creators without actually giving the money to those content creators.
Brave does (did?) not allow creators to opt-out of donation collection and by default opts them in. This means you as a user may think you are donating to your favorite creator but in fact Brave is just holding on to the money.
> Publishers must verify ownership of their properties with Brave in order to receive contributions from Brave users. If a publisher has not verified ownership, then a user’s contributions will be held in reserve inside the browser for 90 days. The browser routinely updates an internal list of all verified publishers to determine whether a property can receive contributions. At the end of the 90 day period, any contributions marked for unverified publishers will be released back to the wallet. No funds leave the browser except to go to verified creators.
Certainly losing his technical talent is likely to have contributed to the problems, but I suspect it's 100x more of Chrome's dominance and Mozilla's reliance on Google's search engine contracts for revenue.