Serrations are not a marketing gimmick that claim is false. A plain edge blade can not do everything a serrated edge blade can do, nor vice versa that is also false. Every design has it's strengths and weaknesses.
Serrations grab, rip, and saw they cut things things like thick leather or thick tough rope better. While a plain edge can cut these things well also it is more likely to do a fair share of glancing, sliding, and gliding requiring more cuts.
Serrations also offer more blade surface area due the curved scallops and when those scallops get dull you can still use the points to do a fair amount of sawing.
On the bad side badly dulled serrations are a nightmare to profile and sharpen. However if they are maintained properly it's no problem. In the wilderness I would not want serrated due to the fact I can run into sharpening problems if I lose my rods and most of my wilderness chores would not require serrations.
I wouldn't use serrations to baton and a plain edge is just as good and better in a lot of instances for whittling,food preparation, and skinning.
For someone like me in an urban environment who does not camp or do much fine whittling, or any skinning for EDC a serrated edge suits me much better. For rescue work I pick serrated hands down. For high adrenaline situations, I would rather rip away with a serrated than slice, glance, and prance with a plain edge. For just cutting things like boxes and stuff again serrated. There is a reason why sailers like serrations.
Partial serrations can be handy but I prefer either full serrations or plain edge. I think partial serrations on a plain edge cheat you out of the full capabilities of both, less so however with longer blades.
Don't knock serrations like a plain edge they have their uses.