I have been mouseless for over 30 years. (The office being the exception but I still use it minimally.)
The issue is not speed, it's control. Precision, if you will. I can automate repeated tasks with the keyboard. Doing that with the mouse is beyond awkward; it's counterintuitive.
Mouse is for interaction. Keyboard is for automation.
(Obviously for some tasks, e.g., ones involving graphics, we need a mouse.)
Is automation faster than interaction. You tell me. Try doing everything your computer does by hand. I will give you $50 million for your efforts. Then report back with your discoveries.
Generally no one (seriously) programs a computer exclusively with a mouse. A keyboard is used. Surely, there must be a reason for this.
Of course, the "tech" company model of the world needs users to not be programmers. The mouse is taken as a signal "we have a human on the line". Automation is taken as a signal "it's a bot". Truly, the only significant difference between the two is that it is far more difficult to manipulate, analyse and serve ads to "bots" and charge advertisers money for it. Users who can program the computer to automate tasks can escape online advertising and tracking in ways that others cannot.