Out in the Pacific Northwest, what can devastate early greens are hungry slugs and rain. WIth both of these an issue, I typically don't mulch greens or tender young seedlings, especially early in the season. Mulch holds in too much moisture and is a great hiding place for slugs to live and reproduce. That said, a thin layer of fine compost will limit the splashing of mud and is too small in structure to provide much of a hiding place.
Mulch can be used more successfully later in the season, but mainly on mid to long season veggies, such as beans or tomatoes.