better way to try out builds?

I wish in poe and poe2, after completing the campaign fully on one character, you could unlock the feature of creating more characters that are already at level 65, and have all their skillpoints (no ascendencies). they would be cut off from trading and guilds, to prevent them from being used for botting maps. however, they could be used to try out new builds directly ingame, without the pain of going through the campaign again, because levelling up slowly when you have already reached maps feels sluggish and painful. and you could find out sooner if the new build you made actually works or not.

thoughts on why this could or could not work?