No live microorganisms survive after baking, but because the food is fermented to start with, it already has a list of benefits.
During fermentation the yeast and the bacteria predigest the starches which makes it easy on us to digest and also puts many beneficial enzymes in the bread that helps us digest better. Gluten is also more digestible and makes it easier for us to digest vitamins, minerals and other micronutrients. It also contains lactic acid, which lowers the glycemic index of the bread. This requires less insulin and causes less of an insulin spike.
In other words, consuming sourdough is a much better and healthier choice.