If I want to be a weapons master, as an easy example, why not follow the same arc? Half way through the campaign, I'm the weapons master and now there's a whole lot more story.
I'm still not certain what a 'weapons master' is, but it's now probably halfway through the story and I have a 6th level fighter PC in my group who I would consider a 'weapons master'. Certainly he has the 'weapons mastery' feat. Certainly he is from the perspective of the campaign, a one man (well, one hobgoblin) army, capable of defeating in need probably 2 dozen or more foes in single battle. NPCs hold him in awe and terror.
Using Elf Witch's Necromancer example - it's not unreasonable to think that "Necromancer" begins when you can animate dead. There might be other starting points, but, that's a pretty big one. For a wizard, that's seventh level. If Elf Witch was in Celebrim's campaign, she had to wait three years to reach that point. That's a pretty long wait to achieve the character you want to play.
Who says? Animate Dead is only 4th level because it has a permanent effect. In my game, even a 0th level apprentice can reanimate wasps and rats for a short period using 'Least Animation'. At first level, you can cast Undead Minions to start animating animals for short durations. It's quite possible to build a character that takes control over lesser undead like skeletons and zombies and orders them around as minion beginning around 2nd level, even if you can't permanently animate them yourself - essentially turning the skeletons and zombies you typically find in dungeons at that level into resources. Third level brings you a 2nd level spell slot and 'Ambulatory Dead', which is an animate dead spell with a duration of concentration.
I honestly don't know whether 3.5 brought low level undead animation/control options to Wizards, but considering the obviousness of doing that I'd be surprised if it hadn't done so somewhere in its vast array of (generally low quality) splatbooks if you went looking.
One of the reasons I was asking, "What does being a Necromancer mean to you?", is I'm honestly curious about what I'd need to do to provide for the feel of being a Necromancer to someone who was apparently hard to please beginning at as early of point as possible. I'm trying to finish my version of the Player's Handbook in a definitive way, and improved support for Necromancers, Psychics, and Illusionist concepts is high on the 'to do' list.
And, Forever Slayer, you've still failed to prove that levelling is significantly faster in later editions. That's a very contentious point. Like I said, I've always seen play at about 4-6 sessions (and 3-5 hour sessions by and large) since the early 80's and we always advanced at about the same rate.
It's hard to do a direct comparison for several reasons. One of them is that 1e was non-linear. Each additional level required as much XP as all the levels before it, and after name level additional levels involved hundreds of thousands of XP while monsters themselves generally capped out at a few hundred XP each. As I recall from 1e, leveling started out reasonably fast and then generally ground to a halt at 10th level. I happen to know that in the longest running 1e campaign I was in, levels every 10th level were taking like 30-40 5 hour sessions each. And I think the only reason anyone was gaining levels even then was we were giving Battlesystem commander's shares of the mass combat XP.
Now, on the other hand if you played 1e adventure paths like GDQ, characters were power leveled through high levels by enormous piles of treasure far in excess of anything suggested by the rules anywhere else - either the MM or the DMG. I know. Because I've calculated average returns in treasure XP for monsters by the rules, and its nowhere enough to level up anyone to high level. For example, for Demogorgon the average expected treasure is: 2000 gp, 1750 pp, 10 gems, 3 jewelry, 2 potions, ~1 scroll, ~2 magic items (not potions or scrolls). Demogorgon is worth 74000 XP per the 1e DMG, so even if you are powering through the fiend lords, your party of 6-8 1e name level characters is going to need a lot more than 13 encounters to level.
As the thread you earlier linked to noted, Gygax had ran his table for 4 years of fervent play and no one had gotten above 14th level in that time. Then again, 14th level in Greyhawk was - aside from pet Gygax NPCs - quite fully puissant.