It is all a bit mad, IMO.
26,36,46 up front, and your choice of 8 on the back was pretty optimum for general riding (touring, commuting and audax).
Marketing just messed it up from then on.
I'm not so sure I'd agree.
The biggest 8 speed cassette I can find is an 11-34. That means a ratio of 1.31 for your lowest gear, and 4.18 at the top. Or 1.6 MOD -> 8.9MOD. At 90RPM the top speed would be 47.8kph. At 60rpm on a hill in bottom gear you'd get 5.8kph.
Conversely, my 28/38 front and 11-40 rear cassette gives you:
1.5MOD -> 7.4MOD. Which is a 60rpm climber of 5.3kph and a 90rpm top speed of 39.5kph.
For a touring setup, I'd have to ask the question. When are you going to be actively in need of pedalling faster than 40kph? If it's going down hill, enjoy the leg rest, it's a tour afterall. With the 3x8 you have the mental load of making sure that you use the right combo of chain ring and sprocket at any given time. The 11-34 8 speed cassette has 11-13-15-17-20-23-26-34, but your 26 is best with the 23,26,34, the 36 with the 23,20,17,15, and the 46 with the 11,13,15. The range is ok, but you actually only have 10 usable gears. Conversely with my 2x11, the big ring works with all 11 gears, whilst the small ring is ok with the bottom 4 gears, Giving me 15 options. My di2 also offloads all of this processing...
Now, if I was to make this a 1x11 setup, my choice of front chain ring would require me to lose something either at the top end, or the bottom end. If I was to use just one of my chainrings, that would give me either a new top speed of 29.1kph, or a new low speed of 7.2kph.
Some might say that a 38/40 bottom gear is plenty, they are also the sort that say that a 1:1 is plenty for anyone.
And this is where I'm going to get all radical and start annoying people with my standard rant about the shitness of gearing on off the shelf bikes.
The sting has been taken out of the rant a little by the arrival of shimano's 30/46 GRX chainsets, this makes for a much more sensible offerings, except for the fact that the largest cassette they offer in a 2x11 setup is 11-34. So the lowest gear is 1.13 or 1.9MOD. This is the point where a man will tell me that this is plenty low enough for anybody. Noone needs a lower gear on the road etc...
To which I call bullshit. I'm sure most men can start off with a bike with a 1:1 lowest gear, and will get up most hills etc...
But for any woman new to cycling, who's just bought a bike and wants to start riding, this gear is going to be too low for all but the shortest of hills. If we want cycling to be accessible to all, we need to get away from the elitist bullshit. GRX is a good start for this, but IMHO the 1x options still do not give enough range for most people, with too large a steps, and the 2x11 options really need to allow for bigger cassettes within spec*.
Your average human, of any gender, should be able to walk into a bike shop with €1000 in cash, and walk out with a bike that fits them, that they can ride up most stuff. Sure they might be slow, they may have to walk the 10%+ stuff, but right now, that's very hard with of the shelf bikes, and the 1x stuff doesn't make it any easier.
There is no right answer, but some answers are more wrong than others...
J
*I've seen people claim that they can get an 11-40 to work with the RX815 or RX817 rear mech, and I've heard similar about it working with the ultegra rear mech. But it's without the spec, and may not work for everyone...