How do newly chreated characters / new players supposed to progress naturually

[Kallera]

I feel this would only serve to make them take longer and be potentially less appealing to a majority of end game players, for the sake of the minority who actually want them to be a challenge while no longer relevant...

It isn't for the difficulty. there can be large disparities between the ilvl of players that enter tge content as it is. New players that go into these fight with a decked out player, if they are a tank or healer role, may find it difficult to perform their role due to the vast difference in damage output and speed in dungeon attempts which leads to deaths and/or arguing.