He offers a clue: "[...] I was surprised to discover how little math is involved in day-to-day programming, especially for a web developer."
As commented in another reply:
... Never used more than a trivial amount of the math
content, but the math processes of thought have been
invaluable.
How many people are crap at something, realise they can get along without it, and thereby conclude that it's useless? Most. It's like being incompetent and unaware of it. It's an unknown unknown.
I think your assumption is that people think like: I like programming. I'm bad at math. Math doesn't help my programming anyways.
Instead I think people think like: I like programming I'm bad at math, so I don't like it. I'm going to look at other fields to improve my programming.
I think the problem is, and the author hints at it, is that people tend to over glorify the importance of math at the expense of drowning out other fields, like prose.
In some fields like web programming, I would say that yes, my time is better spent learning how to write understandable code instead of how to solve complex equations. As a result, I probably won't ever program video games, but thats ok, games take a lot of math, and I wouldn't enjoy that anyways. It's not that I'm lazy and just don't want to get better at programming. I just want to get better at programming in ways that I enjoy the most.
With infinite time, I would certainly do it both.
I would say that yes, my time is better spent learning
how to write understandable code instead of how to
solve complex equations.
I don't solve complex equations, and yet I use math every day.
The problem I see is that people who might be really really good at advanced math are often completely turned off by high school math and the teaching thereof. Hence they never get the chance to see the really fun stuff that turns out to be useful in unexpected ways. Even more, I'd guess that the really good programmers who hate math are in that group.
I would so like to be able to test that hypothesis. There's a Ph.D. waiting in it.
That said, to re-summarize my point tersely: If someone doesn't like a particular field, I still feel that they can be successful programmers by focusing on fields that they do like which are also useful.
The reverse is also true. If you know a lot of math, you don't really know how you might have gotten along as a programmer without it.
You might know that you would have struggled at the mathy programming you have done, but you wouldn't necessarily know if you would have excelled at other kinds of programming despite a lack of math depth.