Paper lengths, and reasonable assumptions in ML conferences. [D]

I've usually been commenting on threads on conference reviews. I'm now expressing my observations here. To the best of my knowledge, paper lengths have been held constant at many conferences, and some conferences have "unlimited appendices" (e.g. NeurIPS / ICML / AAAI / ....) Historically, this was probably due to cost of printing for proceedings, but now, I suspect it's also to prevent reviewer fatigue. However, I wonder if this unfairly penalizes more theoretical papers. Some background: I usually publish theoretical papers at conferences. Some get in. Those that don't, are surprisingly not because of the theory, but because of (what I feel) arbitrary reasons. This leads to this post, which contains some of my musings. In general, the amount of pre-requisite knowledge required to understand a theory paper must necessarily increase. I don't know how to quantify this, but I would expect basic linear algebra, discrete math to be a "given", and more knowledge for each subfield. To also be intellectually honest, recent work should also be cited, especially if your work builds onto it, or is inspired by it. But technical details of recent work should be left to the reviewer to look up, or be put in the appendix. What pisses me off recently is that I've seen more reviewers reject papers based on things like: "The concept is difficult", or "Certain terminology is not explained.", "While the intuition is given before the math, the math could be made easier to read." I've also seen comments like: "The paper makes comparisons to X, but X should be described in detail", and then shifting of goalposts to "The paper makes comparisons to X, but X should be described in detail in the main paper." I would say that half of the rejections I get are based on the AC echoing these points, rather on impact of work, etc. Which puzzles me a lot, given that these ACs might also be professors at universities, and they must have seen similar statements from students. For example: "The {very