Comment by eloisant

The thing is that in 2020 it was too late. Firefox have been lagging behind Chrome for so long, that the headstart they had when Chrome was launched didn't matter.

For example, Chrome had process in tabs when it was released in 2008. Firefox had a ticket in bugzilla open by the community that had been ignored by Mozilla for years, before Chrome was released. Even when it was released, Mozilla's first reaction was "meh, we don't need that".