Adding an attribute to an armour piece or a tool removes the vanilla values associated with it

This issue appears to be similar to other issues about attributes but I'm not sure if its the same, if I give myself a diamond sword with:

/give @p minecraft:diamond_sword{AttributeModifiers:[{AttributeName:"generic.attackSpeed",Name:"generic.attackSpeed",Amount:1,Operation:0,UUIDLeast:944859,UUIDMost:918837,Slot:"mainhand"}]} 1

It gives me a diamond sword BUT does not put the vanilla characteristics like attack_damage 7 and seems to also remove the default attack speed, so this item ends up doing half a heart of damage with an attack speed of "+1"

however typing 

/give @p minecraft:diamond_sword{AttributeModifiers:[{AttributeName:"generic.attackSpeed",Name:"generic.attackSpeed",Amount:1.6,Operation:0,UUIDLeast:944859,UUIDMost:918837,Slot:"mainhand"},{AttributeName:"generic.attackDamage",Name:"generic.attackDamage",Amount:7,Operation:0,UUIDLeast:825272,UUIDMost:961316}]} 1

gives me the same affects as a default diamond sword. this seems to happen with all tools and armour pieces

so to that effect, is adding an attribute to something suppose to then invalidate the default vanilla attack speed and attack damage, or is this a bug?