I think Preach said it best. Or maybe it was from an Asmongold video where he quoted one of his viewers:
Anyway, it went something like "It's not that we want to switch covenants on the fly, and change our entire appearance and place in the lore. It's the systems and abilities tied to those covenants that are the pressure point."
The problem is that Blizzard has tied everything under a single umbrella: Covenant signature abilities, soulbinds, and conduits. They're attempting to mesh the RPG roleplay choice of covenant identity to the underlying gameplay mechanics. And quite frankly, I and many others believe that they're failing to do that in a manner that's going to be fair or balanced.
I'm not against having more impactful roleplaying choices. But they do not need to be needlessly tied to important performance-related abilities and attributes when they don't even make any sense within the context of the story. Bellular made this point in one of his lore videos about how the Maw-Walker(the PC) is helping everyone, and it actually makes a LOT of sense that he/she would have access to multiple abilities from several or all of the covenants.
And I will grant: If this was a permanent choice, such as a sub-class or something that would alter our characters for the remainder of the game's lifespan, I could stomach it. But it's not. It's a choice about a rental power that will change from patch to patch, and go away next expansion.
Players constantly switch specs. They constant switch talents. They can change their appearance on the fly via xmog, and even their hair, skin, and gender in the barber shop. They swap gear CONSTANTLY. But suddenly we're supposed to accept that a rental power that's little better than a talent is meaningful enough to warrant being semi-permanent? That's just now how WoW is played!