Those bonuses, contradictory or not, are so small that in the long run they will barely matter to anyone but someone who wants things to be extremely optimized..
That will be me then

You are of course correct that it doesn't matter when at level 8 you get +6 items.
At the moment I'm trying to do a single rogue and it is difficult for me. I can't get to level 4.
I've spent hundreds of hours trying but I'm stuck - I only need 3000 XP but I can't get it. When I get level 4 the game will be easy (probably)
And that is why I enjoy it