I can safely guarantee you that my tank who’s specifically equipped for m+ will be much stronger in m+ than my tank who’s specifically equipped for raiding, in Shadowlands.
My main will be the strongest in Raiding, my M+ char will be the strongest in M+ and my pvp char will only be strong in PvP. That’s what Soulbinds and Conduits barrel down to. Pick a character for each aspect of the game, rather than play all aspects.
Right now, my main can switch between TD gear for raiding and versa gear for m+ and is equally valuable in both contents, given the option to switch azerite traits without cooldown, talents without cooldown and essences without cooldown. I’ve invested a fair bit of time into getting him there, but he got there.
In Shadowlands, I won’t be able to bring my main, my raid char, up to the same level of competitiveness for both raiding as well as m+. I’ll have to choose, one a weekly cooldown, which content I want to be best in.
So no, my main won’t be my strongest and most effective character, because I’ll be playing three different characters of the same class to make up for blatantly obvious issues with covenants and soulbinds. My PvP char will be most effective and strong in PvP, my m+ char will be most effective and strong in m+ and my main will be most effective and strong in raiding.
Can I do every other content with every single one of them? Sure, I can.
But can I do it as well as if I’ve had a better covenant, conduit or soulbinds? Nope. And that’s the issue here.
Of course you can clear every content as every class / spec / conduit / soulbind / covenant combination (what a world we live in, to go from class / spec combination to class / spec / conduit / soulbind / covenant).
But can you also clear it while being as effective as somebody else, with the exact same gear, talents, spec, race, class but different soulbinds, conduits and covenants? No you can’t.
I don’t know about you, but I don’t like dragging down people because I liked a certain transmog more. And that’s the issue many people have.
Why not both? In wotlk, we had playable alts that were somewhat easily brought up to par, both in level as well as equipment AND we have had the option of switching to one out of two specs, without any issue whatsoever. Get your gear, pay that bit of gold for dual talent spec and you’re good to go to play two different specs without any friction.
Why is “Either you have weaker mains or unplayable alts” even the option given? There’s no good reason why we’d have to decide between one or the other, let’s be real.