> .. it should avoid the problems we'd been seeing with overly small /dev/shm in container environments (which were causing serious problems for using Firefox for automated testing of frontend projects).

docker has a 64M default for /dev/shm that can be overridden, but in hosted CIs it is not always accessible. Chrome is a user of the IPC shared memory too and trips over it in pipelines because of the low default. They track memfd_create at https://bugs.chromium.org/p/chromium/issues/detail?id=798221