Are start-maps necessary?

Start maps are a tool, mainly to help with consistency. But good technique is good technique 

Depends on the type of soil.   Hard pack, you definitely benefit from it because most riders can't control the throttle enough to not get wheel spin at some point in the start straight.   Sand, or horsepower robbing soft dirt - not so much.   I think the Seattle dirt fell closer to the latter category.   But also, I think Kenny has excellent throttle control and technique.

Adrenaline is a big part of this, lots of riders have pulled good starts after some issues on the gate. Also Ken was a great starter long before start maps took over 

This falls into the 'Racer Headspace Logic'  generator. 

Moto 1 Crash in first turn, rip through the field to finish 3rd. 

Moto 2 Holeshot , lead for half the race, fade to 8th. 

RHL 'Should have crashed in first turn again'. 

Mike Alessi agrees...

Ken and Webb both had incidents and barely got the clutch in before the gate drop and both got great starts. Perhaps both had to rely on instinct since they were distracted. 
Like the great philosopher JT$ said, professionals practice till they can’t get it wrong. 

I think the high intensity is what made his great start happen. He was shitting his pants and was hyperfocused in seconds. 

As far as start maps, my 21 Honda it felt like it was cheating paired with tamer front and rear holeshot devices. Hold it wide, dump clutch (quite literally), instant acceleration and traction. My yamaha, i dont like it so i don't use it.