Canned tomatoes with too much vinegar

It doesn't look like it'd make much difference to that recipe. The juice goes in right after the tomatoes, so it's not like they cook on their own significantly. The one thing you get out of adding the tomatoes first is a way to get them spread evenly around the pan without having to stir, so they're mostly on top of the onions and get gentler heat at first. But you'll be stirring soon anyway, so just dumping it all in wouldn't make much difference at all.

Canned tomatoes, compared to fresh, are:

• Cooked. As part of the canning process, they are fully cooked.
• Peeled. Most canned tomatoes are peeled
• Acidic. For safety reasons, canned tomatoes often have additional citric acid added to the can (this prevents botulism growth)
• Ripe. The tomatoes to be canned are often vine ripened to a more ideal ripeness than retail tomatoes, and then immediately harvested, processed and canned.

Most of these attributes are actually an advantage in creating a pizza sauce, and so starting with a quality canned tomato may be far more convenient and flavorful than starting with raw tomatoes.