Originally Posted by
Melchior
They want to make the choice as "fuzzy" as possible, when it comes to theorycrafting.
Covenants have a lot of different choices within them (not just that one class ability), they are more easily compared to class choices than an individual talent, azerite power or essence.
To ask "Which covenant is best for my spec?" will be like asking "Which is best for raids, mage or warlock?" The answer is a lot less clear and varied.
There will always be a mathematically best solution in any given scenario, but you can say the same for mage or warlock in any given scenario... Does that mean you switch characters every mythic raid boss? No. There's a range of how optimal you decide you want or need to be... almost nobody switches class for every fight, but some might change a talent or two. Covenants are in between those choices, leaning more towards a class choice.
Any covenant choice won't be mathematically ideal in every scenario, and it won't be painless to switch the whole thing.
If there's a balancing issue, they will obviously try to address that. They've even stated they might just flat out disable certain portions if it proves too hard to balance, like in PvP.
We'll just have to wait and see.