Ever since USS Cole, i suspect all warships have to treat heavy traffic waters as potential threat zones, which means going dark.
Being run over by commercial traffic is also a rather non-trivial threat. Arguably, being run over by a supertanker is going to cause far more damage than anything that will fit on a speedboat.
It's analogous to jaywalking while wearing a cloak of invisibility. :D
Speaking of invisibility... various missile boats/corvettes
Taiwan's so far only Tuo Chiang class corvette (567t full load)
China's Type 022 missile boat. I swear there's something about that super-intense blue in the colour scheme that seems to blow out the saturation of the photos until they look like were taken with a 40 year old point-and-shoot (83 in service, 224t full load)
Finnish Hamina class fast attack craft (4 in service, 250t)
Norwegian Skjold class corvette/FAC (6 in service, 274t full load)
Swedish Visby class corvette (5 in service, 640t)
I noticed that for supposedly stealthy ships, they all have a bunch of dangly bits that would greatly increase RCS