As said before that you fail each time to see it that 75% will not promote to that D2.1 that is so filled with strong teams.
D2.2 currently has 5 teams that are not bot, D2.3 has 1 and D2.4 has 1 team. So there would be some time before those leagues become a wall to.
For some teams though the move to JBBL may come a lot to early and will go up there and get beaten down again, but the overall competition of D2 will rise and with time perhaps there will be not such a great difference between D2.1 and the others.
A wall... another definition...
You keep shutting your ears.
As said multiple (too much times to count them...) times before;
The concept of filling all leagues on a certain division evenly has nothing to do with this suggestion.
It can be done w/o this useless suggestion of "starting at a lower (all-BOT) division.
Each of the Div-2 leagues has a demoted from the Div-1 league.
Hence, due to the fact that they are playing the game very long, they are the "wall" that those new users can't pass.
The only chance they have is if that player just left the game.
Then, they will go to the first division, and see what is the real size of a "wall".
It is a fact that this BB-community (not just Nippon) stopped to grow, and is just staying around the low amount of 50K.
The main reason is that wall of uncompetitiveness.