Improving privacy is reducing the quantity and quality of data collected about you. Making changes to Firefox improves privacy because web sites can collect less data about you.

Improving anonymity is reducing the odds that data can uniquely identify you. Making changes to Firefox harms anonymity because very few people deviate from defaults.

For example, turning off Javascript prevents a site from knowing much at all except header information like User-Agent. So it can't draw a canvas fingerprint nor measure your screen resolution, but it can still record the fact Javascript was disabled - a rare event.

OP is correct: the changes make one 'stick out like a sore thumb'; but incorrect in asserting users are 'more fingerprintable'. Improving privacy may reduce anonymity, but losing anonymity does not necessarily affect privacy.