It was good enough for Atlassian to buy the whole company for a good chunk of cash too, if I recall correctly.
The abrupt ending of Arc's development has now left a hole in the market that Firefox could fill and gain marketshare.
Atlassian bought Arc to put AI in it by the way; "Welcoming The Browser Company to Atlassian Building the AI browser for knowledge workers"
https://www.atlassian.com/blog/announcements/atlassian-acqui...
Your cars are computerized death traps? Advertise their reliability.
Your OS sends endless information back home to Apple? Advertise its privacy features.
Your AI hallucinates? Advertise how useful it is for summarizing data.
Both of those require convincing people to use the browser, which is "selling" in the sense of persuasion even though there's no exchange of money at that point.
By "sell" I do not mena to make a profit, I mean, make it visible to the market.
If firefox did its job and got out of the way, who would notice Firefox? It is hard to sell something with no "bells and whistles". Do you think it is a mistake that Liquid Glass exists? No. LG is there so you notice you are on an iPhone which uses to just get out of the way but now is just in my way all the time.
Adding AI to Firefox is to make it visible in the market.
You cannot sell what cannot be seen. Business 101.