It's the anti-fun solution for you, and for those with a playstyle similar to yours.
For me, and those with a playstyle similar to mine, starting above 1st level robs you of the opportunity to develop and get to know your character's early adventuring history. For us, starting above 1st level is the anti-fun solution.
Playstyles differ. There's nothing wrong with that, but I do think there's something wrong with the way you paint your playstyle as objectively correct and mine as automatically horrible and "anti-fun".
You are correct that playstyles differ.
But, there is a difference here you might be missing.
It is actually not fun to play a mook when everyone else is playing Demigods. It's annoying. It's annoying to have a fighter hang in the back or a wizard firing 5 point of damage cantrips that rarely hit or the DM modifying encounters, just to give the PC mooks something to do. It is the exact opposite of fun. It's not that your style is badwrongfun overall especially for you, it's that it's just plain way into not fun and frustrating for myself and many other folk. I suspect that some (or even many) players at many tables who play your way feel that way as well, they just might not express it to the DM (or get overruled).
It might be desirable to develop a PC from scratch, but playing your preferred playstyle wouldn't be much different than starting out a group of PCs at level one while the DM threw in three 15th level NPCs to lead the group. The NPCs would make most of the decisions, the PCs would be the cannon fodder. The players in this case would probably have a lot less fun being the fifth wheels.
In fact, there are a lot of posts all over message boards where players do not like the Elministers of the various gaming worlds. Imagine playing a game where your PC is first level and the wizard PC next to you is a mini-Elminster.
And yes, I have experience in this from GURPS, not D&D, but I'm not seeing a major difference between the two game systems. One of the worst 9 month gaming experiences that I ever had (and I had a lot of great gaming experiences with that same group of people). Your preferred playstyle is fine for you, but I think it totally sucks (it's not just bad, it's awful). So, I stand by my statement that it is abysmally not fun. Obviously, YMMV.
There are playstyle differences that are just not preferred, but are ok overall. I don't prefer to do xyz at a table, but if that's what the table is used to, fine. I'll go with the flow. This is not one of them. This one is just plain beyond terrible. It's a game. Meant to be FUN!!! Why handicap the players of dead PCs so severely? It just doesn't make sense. It's like some players get to eat snacks and drink soda/beer, and other players are forced to sit in the cheap seats and are given a cracker and no water.
And note: I am not talking about being 2 levels below the rest of the party. I'm talking about being 8 or 12 or more levels below the rest of the party. Sure, levels 1 to 3 level pretty quickly, but it's months and months or even a year or more of suckage when there are 12 levels between PCs.