In my remedial algebra class, I assign these stupendously short homeworks, but require precisely written work -- professional format, one full operation per line, justification in words at each step. (I don't have much evidence that it helps the students, but at one point last year I had an emotional meltdown trying to read students' normal math writing, so there you go -- it's quite literally defending my own sanity.)
So on a lot of the homework, inevitably, some fraction of the class leaves out all of the equals signs. And since I go through and just check off each line as being correct or not, this results in every single line being wrong, resulting in zero points for the entire assignment. Even if everything else was correct, even if all the final results are the same as the answer sheet.
So in one sense, kind of brutal. In another sense, this requirement was made abundantly clear in class, including a fully written example from me on the submission page that they're turning it in on. So if you can't follow that simple requirement, one might argue it's an eminently reasonable end result.
But here's another way of looking at it: Each line of math is, effectively, a sentence. (A highly condensed sentence in specialized notation, but the same nonetheless. It can be re-hydrated back into normal English at any time.) And the equals sign is the verb "to be". It's the most important verb in any language! What if someone were in a writing class and submitted a paper without any verbs? What if they were entirely unable to say "you are", "I am", "he is" anything at all? Would an English teacher totally flip out? You bet they would.
And that's exactly my reaction when I see a paper like that.
Complete sentence: 5 + 3 = 8 ("Five plus three is eight.")
Sentence fragment: 5 + 3 8 ("Five plus three eight.")
Repeat that sentence fragment for 10 or 20 problems per page and see what happens to your eyeballs. Slings and arrows and all that.