Most of my PCs multi-class because I don't see the game construct of 'class' as a real thing that exists in the game world. In the world, the creatures cannot be aware of 5E game mechanics! They are no more aware of their 5E 'character class' than they are of their hit point total.
I also like fluffing my PCs as 'half-and-half'. For example, I might say that my (mechanically) human PC has some elven blood: one parent was human and the other half-elven. It allows me to describe them with unusual hair/eyes/ears and so on, and informs my choices regarding my placement of certain ability scores (or explains why those rolls were what they were). But I don't need to create a new PC race: 'quarter-elf'! I just use the mechanics for humans and have my concept inform my choices (or explain my rolls), because the stats must match the concept, whether the concept came first (point-buy) or the stats came first (rolling).
If I wanted to create a dwarf with one hill dwarf parent and one mountain dwarf parent I would pick one for game mechanics but blend the two fluff-wise.
How about this: You like rolling. I don't. End of story.