Having no swap was no panacea, because all of the code sections of your running programs that are memory-mapped in effectively count as "available" clean pages that can be evicted when memory is tight, and they'll cause thrashing just as much as swap would. The solution is to OOM-kill processes before that happens.

Hmm, I personally hasn't experienced any trashing after disabling swap. Instead of the desktop freezing up or heavily lagging for a while until I somehow able to kill some apps to free some memory after 10 minutes struggling to open a terminal, after disabling swap, now it instantly crash back into the login screen when running out of memory.