• You must salt the water.

• You must serve it mixed with the sauce.

I disagree on both.

I've been cooking pasta since I was a kid, and I prepare it the way my mother (who grew up in Rome) did:

• Cook it way less than it says on the box, until it's no longer crunchy but not further.

• Time dinner so that the pasta is the last thing to be ready, where you're eating it within 5min of it coming out of the pot.

• Serve it in one bowl, with the sauce in another.

The primary goal is to keep the tastes and textures distinguishable, merging only as you chew. The pasta resists your teeth; the sauce flows. The sauce is rich and flavorful; the pasta is a hearty foil. Secondarily, by combining only on each person's plate you can handle a range of preferences in sauce-to-pasta ratio, and different dietary restrictions (ex: a separate vegan sauce).

I don't know how people ended up thinking there was only one way to cook pasta, but to my taste the standard approach is a big missed opportunity.