I'm not sure if it is really possible to learn/teach math (like actual math, not just some loose intuitions, because those don't really help you with anything) without going through notation and prior knowledge. Notation exists for a reason.
I wanted a regex one recently. First off, they all presumed mastery of the concept of a string, but more seriously, none of them had a really good definition of a regex! I still can't think of one myself, but I know it's probably not "pattern to match specific strings", because it uses an uncommon meaning of "pattern" and a jargon meaning of "match". And of course they all immediately used terms like "formal languages".
The perldoc page 'perlretut' did pretty well with "a template that is used to determine if a string has certain characteristics" - ok, a bit abstract for my taste, but let's keep going - then a bit further down they use "modifier" (flag) with no definition. But I really had to look hard for flaws in that one. I guess the only way to actually nail this is to supervise successive groups of students as they try to learn using your tutorial-in-progress...
And then an example like "Look, you have your Word document and you are looking for ..."
In the Wikipedia page you linked, I immediately encounter several terms that I do not know the meaning of. I must either click through or search separately to fill in my own gaps.
Your criticism is not totally disagreeable, but we have to wonder where to draw the line. Is a "Hacker's Guide to Numerical Analysis" obligated to hold your hand all the way through basic notation? The notation that you mention in your comment are the "Hello world" of mathematics.
In saying that, in general I've found it's not too bad. Mostly greeks and the occasional symbol like sigma along with some set notation.
The first point explains something as basic as absolute and relative errors. Great.
1 page down (s)he's casually thrown in function notation with R representing the real numbers with no explanation. Anyone who isn't familiar with this notation is immediately intimidated. But I'd wager almost anyone who is familiar with it didn't need to read the page before it. But also, I think it's just unnecessary to be this specific in the first place, if you're trying to quickly explain concepts.
It's actually a huge problem in maths and even Wikipedia (I feel) is pretty guilty of this.
If you take a (relatively) key mathematical concept, such as the Taylor series, then the opening gambit is completely incomprehensible to anyone who isn't already knowledgeable in maths: https://en.wikipedia.org/wiki/Taylor_series
This, to me, seems in huge contrast with other scientific fields. Medicine wikipedia, for example, caters towards the "average reader" first, and doctors later. This is entirely appropriate for an encyclopedia. For example: https://en.wikipedia.org/wiki/AV_nodal_reentrant_tachycardia...