[2023] About class vs role fulfillment

I want to preface this by saying I have no idea if there was any mention anywhere about design philosofy on the role vs class topic, as in, if classes are more locked-in on their role fulfillment or are more free to swap around and simultaneously able to play multiple roles. Feel free to link anything of relevance.

What if the ability to tank is expanded to other classes using their tank secondary archetype?

An Apostle (cleric+tank) with a tank build, like proper point distribution into defense and survivability, a shield, heavy armor set and tank skill augmentations SHOULD be able to tank for a group, especially if you give them defensive auras/buffs from, say, a Bard in the group. Same could be said about Dreadnought (fighter+tank).

Also same for other classes utilizing their tank secondary archetype, to an extent*, since these heavy melee users are more prone to wear plate armor and have more hp and natural survivability and be more tanky and whatnot. Idk I'm just rambling here.

* = lower/medium difficulty content, like an easy open world mob grinding spot or easier dungeons, while sturdier folks are still needed for harder content.

Same question could be asked about the other roles:

If a Knight (tank+fighter) picks up a two handed sword and swaps their build to do more damage, should they be able to be on par, or close to being on par, to a DPS archetype class?

How about a Bard, which historically known as a support class in past games, say, should they pick up a bow and do the same as Song Warden (bard+ranger)? What about the other around? A Soulbow (ranger+cleric) choosing to go with intellect gear/build to play as support and heal their group?

Of course these options would be costly, since to be competitive or useful with all of them you'd have to carry multiple types of gear and weapons, but we're just talking about the possibility. The discussion about functionality and practical use of this feature can come later.

My concern comes from playing other MMOs with the holy trinity style of class design. Putting groups together used to take so long due to the wait for the more rarely played/non-popular class choices, which happened to be support or tank roles.