Absolutely True. But after using WebSearch for some time with an extensive tree, you will have an similarly extensive collection of Attributes. And the WebSearch attributes will be Mixed in with the other Attribute custom types in the menu. Making it difficult to find the Attribute type for a particular Web UUID (And it does not help that this menu does not have alphabetized sorting.) I now clipboard the Attributes most frequently used.
It made sense adopt the UUID labels found as Custom Tags in GEDCOM dialects for some of the Attributes. (Such as _FSFTID for the FamilySearch Family Tree profile identifiers. That tag is supported by RootsMagic, Heredis, Ancestral Quest, Legacy Family Tree, TNG, WikiTree) But these custom Attribute Types can be cryptic when not used on a daily basis.
It seems as though it might be cleaner if the UUID was stored as a Volume/Page field value in the Citation.
BUT before changing anything… it would be reasonable to discover how @SourceAirbender , @clarkegj and @Nick-Hall will be storing UUIDs for the FamilySearch portal targeted for Gramps 6.1 version. Or wait for the FS integration testing key to be made available.