Well, maybe if you live somewhere pretty flat. Or are willing to give up some high-end range (>25 mph). 10/11 speed cassettes generally only have a few teeth wider range than a ~7 speed, for example (e.g., you can get a 13-28 7-speed and the bigger 11 speeds are 11-32 (road)) . Mostly, the jumps are just much closer together, which makes for a smoother shift and easier to find a comfortable gear at a given effort.

> So I sacrifised the very highest and the very lowest gear compared to my old 3x9, but this thing never drops the chain off the front end, there is no front derailleur that always gets bent and fails to shift properly, and there are no awkward momentum-bleeding crazy shift-down-one, shift-up-the-other moves. And you save money, weight and complexity, meaning less maintenance and less failures.

Yeah, there are definitely some benefits! In my area (Seattle) with my level of fitness, I'm a fan of 2x front cogs.