Warped Headband of Intellect sets intelligence to 18 and allows quick meta-gaming builds where intelligence can be made a dump stat.
Also, we are comparing level 4 magic item progress in BG3 vs level 8-10 in BG1.
INT as a dump stat is a trap build that will only pay dividends in early access while we are unable to level past 4. A "stupid" wizard with headband and a greatsword will be weak next to a fighter at level 5 when the fighter gets double attack and the wizard doesn't. The stupid wizard will also not be able to reach 20 int, so they will fall behind the power curve for any spell that allows a save.
Its an uncommon item in 5E Dungeon Masters Guide, which means that the authors feel that it is appropriate loot for characters level 1 and up.