There's some definite trolling down at the bottom half of that page: "Huh? I've seen no objective evidence that BrainFsck is more challenging for business applications and systems software programming than is Lisp. I invite you to provide clear evidence that it is more challenging."

Leaving that aside though, other people smarter and more experienced with Lisp than I have suggested that this "problem" is not unique to Lisp, and may not be a much of a real problem. I really think it's just a question of having good documentation and sensible style which explains what you need to know to use the magic even if it doesn't explain what's underneath. It's true that a lot of "lone hackers" aren't going to be writing good (or any!) documentation, but that's not a Lisp problem.

Ruby's metamagic is a common example. I already know Ruby and recently I've been learning Rails. I know there's a lot of magic going on behind the scenes, and occasionally I'll read some example or something and know that underneath there's magic that I do not entirely understand. I can continue studying the framework as a user and probably even get away using it for a while without completely understanding the magic underneath. I doubt that every person who has used Rails commercially completely understood every part of the framework that they use, since that would be a huge drag on their ability to ship their thing.

Another interesting example: This past week I talked to someone at a nearly pure Scala company and he described this DSL that they wrote (or just use? I can't remember) to interface with SQL databases. It exploited the fact that infix operators are really just methods and that you can define implicit conversions on existing library types that allow you to sort of extend them (I don't actually know Scala, so this may be slightly off base). The snippet of code he showed me, while it looked like Scala, would be turned into an SQL clause. Programmers who use this don't necessarily need to understand all of the gritty details so much as they need to understand what the designer intends and understand the semantics of SQL and of the DSL.

In Common Lisp, "lambda" is a macro. I don't really know how it works, but I know that it expands into lower level code defining a function and a closure. It's the same way with standard macros (in some Lisps) like let, letrec, cond, if, and, or etc... Most Lisp programmers who are not experts can use them understanding that they are macros but maybe not knowing their complete implementation because they are very well defined (and because they are pretty simple).

More complicated macros like "with-open-file" can be used by programmers who probably have some idea of how the macro works, but not a complete understanding. As long as your own macros and Lispy magic are documented sufficiently and designed sensibly programmers should be able to use code in your "world" without understanding it completely. At least to start.

N.B. I haven't used Lisp in a commercial setting, so it's entirely possible all this is bunk and I'm just being naive. Wouldn't be the first time.

edit Upon re-reading this monster comment I realize it might come across that I'm advocating some kind of "cargo cult" or copy-and-paste style of ignorant programming. I'm really not. My point is that while understanding your tools is important, so is knowing when you don't need to peel back the curtain and instead need to address the problem at hand.