In the kitchen, and I’m talking pro chefs here, it is a widely held belief that bread knives and tomato knives should be serrated. The reason this is almost universally believed is because with bread you cut it by sawing to avoid crushing it or deforming it if it is very soft. On crusty breads it is sometimes difficult to get a non-serrated edge to bite.
On tomatoes it is also sometimes difficult to get a polished edge to bite. Also, acidic foods dull an edge quickly.
NONE of these make a serrated knife better. A well done edge will beat a serrated knife every time. But a serrated knife does make cutting breads and tomatoes easier, and for tomatoes you don’t have to continually wipe your blade on a wet towel to get the acids off that are eating the edge.
I talk everyone I can out of serrated knives, but serrated knives do have some utility. But in these cases I recommend the person go get a serrated slicer at Walmart. A serrated knife is intended to be a beater knife and there’s no reason to custom make one from a quality perspective. (read as: I’d much rather make you a fantastic chef knife where the cutting performance and edge retention is night and day versus making you a knife where you can’t tell the difference.)
It goes exactly to what John Doyle said: serrations are a crutch for those who don’t want to sharpen. But in real life sometimes a crutch is useful, non-perfection aside.