It's much, much harder, particularly when you realize
that the Yosemite Decimal System progresses like the
Richter scale, in the sense that a step from 5.13a to
5.13b (an increase of 1 grade unit) is leaps and bounds
harder to achieve than improving from, say, 5.8 to 5.9.
Although this was the myth I was taught (or what us precocious kids must have made ourselves believed, since obv. we were progressing so well/so poorly) as well as a teenager, it's false. The Richter scale goes up logarithmic base 10, so that 2 in magnitude is 10 times more than 1 in magnitude.
Climbing grades don't follow that, nor do they follow a linear pattern, (although they follow MORE closer to a linear pattern...). It's just that 5.10 is harder than 5.9; 5.13b is harder than 5.13a.
There's no mathematically exactitude over it. A 5.13b climb just "feels" harder than a 5.13a climb, and a consensus has been reached. YDS is after all, open ended. If it was logarithmic like the Richter scale, going from 5.13 to 5.14 (5.13a, b, c, d, then 5.14a) would be 100,000x more difficult, which obviously it is not. The original YDS from 5.0 to 5.9 were based on benchmark climbs (not in Yosemite, strangely enough).
Grades afterwards were added as things were getting a little crazy to be calling them, "5.9", so "5.10" was born. This also gives you the peculiarity where established 5.9 climbs are, "harder" than newer 5.10 climbs, and this repeats for 5.10d/5.11a; 5.11d/5.12a, as the scale kept going up.
Then you gotta remember that all the climbing areas in even just this country are geographically isolated, so a 5.9 in Eldorado Canyon is different than a 5.9 at Devil's Lake. Yosemite itself is known to be pretty stiff. Unless you're good at a particular style, then...
Anyways, it's a big mess, and it'll never be fixed. What Ondra is doing is pretty hard. Let's remember he's only 23.
It's like lots of things in sport, actually. Imagine the progression from running a 6 minute mile to a 5 minute mile to a 4 minute mile. Now go to a 3:55 from there. It's a much smaller notch than 6:00 to 5:00, but will take you ten years of training.
So sure, you can consider it just adding more weight to the bar in a linear fashion. It still a lot harder to lift each individual pound as the weight increases.
Actually, I don't consider it like adding weight, since climbing grade difficulty isn't calculated in a way that would be so simple.
There's no objective way climbs are organized in difficulty except by subjective feeling. Holds may be (say) smaller, and/or farther apart, but the difficulty can only be sussed out in a general sense - there's far too many things to take into consideration.
Compounding all this is that a climb could be more/less difficult because of a climber's body type (tall/short climbers excel at different climbs)
So you're left with a consensus, which is living and breathing, not a calculation.
I've always thought of it in the way that if you went to an area like Yosemite or Font (bouldering) - then for every 100 people messing about, then 10 of them would be able to climb (5.12, Font 7a+) and 1 of them would be climbing (5.13, Font 8a).
Those difficulty conversion are possibly way way off and this areas may attract particularly good climbers ... but my point is the scale is logarithmic in the sense of how many people can achieve each tick level.
At least in bouldering, John Gill proposed the, "B" scale, which measured basically how many people were able to top the problem. So if you established a climb, it gets a grade of, "B1", until another person gets sends it "B2". This scale basically favors the hardest problems being the most important, and adjusts the grade of the climbs, as the "sport" progresses.
Gill was a Math professor, so this is somewhat interesting to the discussion. He famously thought of boulders as, "problems", of course.
Yeah, 5.10a -> 5.10b is about the same step up as 5.7 -> 5.8 and the Yosemite Decimal System was indeed developed somewhere other than Yosemite: Tahquitz/Suicide in Southern CA [1] (where many of the golden age climbers and stonemasters honed their skills)
Since the grades are subjective, and largely determined by the first ascentionists, (although through consensus sometimes re-graded) this is not possible. My subjective take on it, up to 5.11+, can't speak for anything beyond that, is that a bump in a grade, any grade is about the same increase in difficulty. My climbing has mostly been in Joshua Tree, Idyllwild, Smith Rocks and a bit in the valley.
Climbing grades don't follow that, nor do they follow a linear pattern, (although they follow MORE closer to a linear pattern...). It's just that 5.10 is harder than 5.9; 5.13b is harder than 5.13a.
There's no mathematically exactitude over it. A 5.13b climb just "feels" harder than a 5.13a climb, and a consensus has been reached. YDS is after all, open ended. If it was logarithmic like the Richter scale, going from 5.13 to 5.14 (5.13a, b, c, d, then 5.14a) would be 100,000x more difficult, which obviously it is not. The original YDS from 5.0 to 5.9 were based on benchmark climbs (not in Yosemite, strangely enough).
Grades afterwards were added as things were getting a little crazy to be calling them, "5.9", so "5.10" was born. This also gives you the peculiarity where established 5.9 climbs are, "harder" than newer 5.10 climbs, and this repeats for 5.10d/5.11a; 5.11d/5.12a, as the scale kept going up.
Then you gotta remember that all the climbing areas in even just this country are geographically isolated, so a 5.9 in Eldorado Canyon is different than a 5.9 at Devil's Lake. Yosemite itself is known to be pretty stiff. Unless you're good at a particular style, then...
Anyways, it's a big mess, and it'll never be fixed. What Ondra is doing is pretty hard. Let's remember he's only 23.