I read that YAML frontmatter isn't supported by the app for exports and I understand the reasons.
However, when importing makrdown files, users coming from many other Systems (Obsidian, Foam, Dendron, Logseq etc.) that are based on markdown files will have many YAML frontmatter properties in them. Manually converting them to Attributes in SiYuan is not an option most of the time.
It would be very nice if the Importer could transform most if not all YAML properties into Attributes automatically.