What if students learned "Force = mass * acceleration", and only later moved to "F = ma" once they'd gotten tired of writing it, instead of smacking students in the face with "F = ma" right out of the gate, to say nothing of all the other stuff we smack them with right away?
Sets? Define a set semantically, then replace "set" with S. Vector spaces? Define a vector space semantically, then replace "vector space" with V. Limits? Define a limit semantically, then replace the word with "lim".
Moreover mathematicians typically use jargon in a more reader-friendly way than simply throwing obtuse equations at them. Expressions, equations, inequalities and identities are complements to the proof, not the proofs themselves. Best practice holds that you present a theorem in plain language alongside the necessary notation, then break its proof down into as many atomic units (lemmas, propositions, corollaries, etc) as possible. Here is a blog post[1] from Terence Tao giving general advice for why that's useful. Tao has written a bunch[2] of these on the theme of emphasizing exposition and clarity.
Also contrary to popular belief, well-written mathematics papers actually have quite a lot of exposition in them. For a famous example, look at Yitang Zhang's proof[3] that there are infinitely many primes with 70 million numbers (or fewer) in between them. He spends a full five pages on introduction, background results used to develop the proof, and (most importantly) notation. He also includes a "sketch" of the proof in broad strokes so that a reader can follow his arguments at both a high level and in gritty detail.
That doesn't mean papers like Zhang's are accessible to most people. The jargon is still there and you can't really change that unless you want papers to become self-contained monographs. But the point is that what you're proposing - concepts defined in a straightforward way before moving on to dense notation - is already the general practice.
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1. https://terrytao.wordpress.com/advice-on-writing-papers/crea...
Anyway, in sometimes it is useful to write more. For example teaching https://en.wikipedia.org/wiki/Consistent_and_inconsistent_eq... I try to write the full name of the classification at least for two clases. It is painful, but it is worth. I teach in Spanish, so we have also the problem that underdetermined is "indeterminado", so a capital "I" can mean "Inconsistent" or "[I]underdetermined" or in one of the following clases "Independent" (like in a linear independent set of vectors, yes they mix this too). So it is important to use the full name (or a long enough abbreviation) until you are sure that everyone can understand which "I" you are writing.
But this is not clear enough. What force? What acceleration? More precisely, what is the direction of the acceleration? The original statement of this law is less ambiguous: "Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum lineam rectam qua vis illa imprimitur. "
Or, in plain english: "The alteration of motion is ever proportional to the motive force impress'd; and is made in the direction of the right line in which that force is impress'd"
There! we are good to go. Now write the fundamental theorem of calculus in english, readable by everybody, without those ugly, unreadable variables and fancy symbols...
[1]: AIUI, the actual problem the original "New Math" had. The original "New Math" tried to start students with set theory, because that was the foundations of mathematics, so obviously, the best place to start an education, right? (Hint: No.) This is why parents said they didn't understand "New Math". By comparison "Common Core" math is all-but-identical to what I learned in school 30 years ago.
(and I may add that all programming should do the same).
I also agree with you that starting math with set theory is utterly ridiculous and even harmful. You should start with arithmetic and with geometry (obviously, using single-letter variables when needed).
I'm more used to math than to code, and I find multiple-letter variables ridiculous when not unreadable.
In the ancient times, mathematicians used to write formulas using latin sentences. Even the simplest arithmetic result occupied a few lines of text. Are you proposing that we go back to that age?