That is a weird alternative history. Even by Firefox 1.0, it was a dramatically better browser than MSIE in every conceivable metric -- except for support for Microsoft's proprietary extensions like VBScript, ActiveX, and NTLM auth support. (It also failed to replicate some of MSIE's most outrageously terrible bugs.)

When Chrome was released, Firefox was four years old and had already gained 33% market share with momentum on its side, mostly through word of mouth. Chrome was a bit better in some respects, a bit worse in others, but it had the Google marketing juggernaut allowing its market share to skyrocket.

chrome started picking up on firefox when they released 4.0 and started doing some heavy UI updates which made it feel chonky, whereas chrome was this smooth looking browser that paid attention to webview realestate by putting the tabs in the topbar