The terms relaxed, acquire, and release refer to how an atomic operation is ordered against other accesses to memory.
Counter to what the article states, a relaxed atomic is still atomic, meaning that it cannot tear and, for RMW atomic, no other access can go between the read and the write. But a relaxed atomic does not order other accesses, which can lead to unintuitive outcomes.
By contrast, once you've observed another thread's release store with an acquire load, you're guaranteed that your subsequent memory accesses "happen after" all of the other thread's accesses from before that release store -- which is what you'd intuitively expect, it's just that in modern systems (which are really highly distributed systems even on a single chip) there's a cost to establishing this kind of guarantee, which is why you can opt out of it with relaxed atomics if you know what you're doing.
https://en.wikipedia.org/wiki/False_sharing
Rather than incrementing each counter by one, dither the counters to reduce cache conflicts? So what if the dequeue becomes a bit fuzzy. Make the queue a bit longer, so everyone survives at least as long as they would have survived before.
Or simply use a prime length queue, and change what +1 means, so one's stride is longer than the cache conflict concern. Any stride will generate the full cyclic group, for a prime.
Cambridge, MA but still ... unexpected.
If someone hands you a blank board representing the complex numbers, and offers to tell you either the sum or the product of any two places you put your fingers, you can work out most of the board rather quickly. There remains which way to flip the board, which way is up? +i and -i both square to -1.
This symmetry is the camel's nose under the tent of Galois theory, described in 1831 by Évariste Galois before he died in a duel at age twenty. This is one of the most amazing confluences of ideas in mathematics. It for example explains why we have the quadratic formula, and formulas solving degree 3 and 4 polynomials, but no general formula for degree 5. The symmetry of the complex plane is a toggle switch which corresponds to a square root. The symmetries of degree 3 and 4 polynomials are more involved, but can all be again translated to various square roots, cube roots... Degree 5 can exhibit an alien group of symmetries that defies such a translation.
The Greeks couldn't trisect an angle using a ruler and compass. Turns out the quantity they needed exists, but couldn't be described in their notation.
Integrating a bell curve from statistics doesn't have a closed form in the notation we study in calculus, but the function exists. Statisticians just said "oh, that function" and gave it a new name.
Roots of a degree 5 polynomial exist, but again can't be described in the primitive notation of square roots, cube roots... One needs to make peace with the new "simple group" that Galois found.
This is arguably the most mind blowing thing one learns in an undergraduate math education.