I don't think single character/spec is "playing as intended" for most of us.

[Omedon]

Do you feel that the single character/spec playstyle is supported or intended any more in WoW?

I don’t. And I’m totally ok with it. I just counted my HoA’s account wide (via altoholic addon) at 21 this weekend, and I have 4 more pre-110 alts to level before 8.2. You could say that azerite being a pain to fill out and min/max for multiple specs supports staying on one spec, but then you look at their answers on this topic’s feedback: “farm more, carry multiple sets,” etc. They know you’ll want to play multiples and they figured that into your sticking around longer to do that… or doing what I do and just speccing generalist traits or flushing your azerite perks completely in your offspec, which is also fine for most specs in most content in the game.

But seriously, unless you’re looking at the top raiders in the world or mega competitive M+ Pushers… can you really say that Blizzard really prefers or supports your playing just one character, just one spec, particularly with them splitting the storytelling like this? “Declare your allegiance” may turn out to be a double entendre or something other than standard factionalism by the end of it all, but I certainly don’t see that as an encouragement to only play one character… because there isn’t such an encouragement, IMO. Quite the opposite really.

[Rixxis]

When has anyone said you should only stick to a single spec? At the top end of mythic progression is the most alt'ing and class stacking you will ever see. THe casual player can afford to just play 1 thing if they love it because its viability doesn't really prevent them from seeing content. I don't think this game has tried to emphasize playing a spec since they introduced dual spec'ing in WotLK.