On: The Linux Edge (1999)

[pvg]

It seems more like questionable reading and strange selective quoting than poor writing. The writing as written is pretty standard - first sentence is the thesis and the rest of the paragraph supports it:

The first very basic rule is to avoid interfaces. If someone wants to add something that involves a new system interface you need to be exceptionally careful. Once you give an interface to users they will start coding to it and once somebody starts coding to it you are stuck with it. Do you want to support the exact same interface for the rest of your system’s life?

[jimbokun → pvg]

He meant to say "Avoid unnecessary proliferation of interfaces", but said "avoid interfaces" without any qualifiers, which makes zero sense.

Sure, I figured out what he meant a few paragraphs later, but his writing made it much more difficult than it needed to be.

[pvg → jimbokun]

I think you might have just missed it on a quick scan when you first read it. The broader notion is in the paragraph before. The paragraph with the sentence itself is specifically about that - it lays out a very standard 'design by contract' sort of argument. It's not true that there are 'no qualifiers', the immediate surrounding context is plenty of qualification.