What is wrong with having most of your character done beforehand, knowing full well that the DM was present when character concepts were discussed? What is wrong with having everything but the background (which he wanted to coordinate) done? Doesn't it save time? What else can be added to the character other than class, equipment, and spells that can't be done beforehand? Not only that, but he approved all character concepts!Huh? Why you so mean? Sigh.
If a DM invites you to his game, and asks you to not create characters until everybody meets for "Session 0" to create characters together . . . . and you ignore that . . . .
I'm not sure Hussar is the DM for me, and likely vice versa, but that part of his frustration I'm fully understanding of.