The people with SSD thrashing didn't experience excessive application memory usage, so that doesn't add up. By all indications it was an issue where the kernel

The people with SSD thrashing didn't experience excessive application memory usage, so that doesn't add up. By all indications it was an issue where the kernel aggressively swaps in and out under some conditions, even when real memory pressure isn't that high. Memory leaks don't cause swap thrashing most of the time; the leaked memory gets swapped out and then just sits there, as it is unused (hence leaked).