On smaller heaps it was already possible to get 5-10ms pauses with the (now deprecated) CMS collector. Unlike Z it was a non-compacting collector though and had some ugly worst-case behaviors.
Yeah, CMS is great until it isn't, and then it ruins your whole day. A bit of a black art to get tuned well, too, and when your workload changes slightly your tuning is no longer effective and the world stops for 30+ seconds. Hopefully ZGC will be more like G1 in terms of "feed it some extra memory and set a latency target" being all the tuning you need most of the time.