Nod. And, really, at bottom those're just the kinds of concessions game makes to being played by a group, rather than a solo player & DM. Class is another.
True. And really, while most of my post was tongue in cheek, there are certain character concepts that really only work in a solo game where your character is the focus of all the action and plots.
Or just don't work in a "game" setting at all - they are meant for characters in a story and many story tropes simply don't work reliably in a game were dice rather than author fiat determines the outcome.
The plucky underdog who survives by luck and outwitting his opponents? Dead in the first round. A crit by an orc with a greataxes doesn't care how smart or plucky you are.
The brooding lone hero? Killed by the first pack of goblins he runs into. He may be a badass, but numbers count for more.
D&D at it's base is a game about a group of mercenaries killing monsters and taking their stuff. We layer background stories and RP concepts on top of that, but your character needs to be able to function in that role in addition to whatever else you want for them or you generally will have a bad time.
Other game systems handle low-combat, highly social stories better than D&D. D&D handles fantasy combat and monsters better than most.