Encumbrance rules no matter the edition never stand-up to much scrutiny. Best leave that out of the discussion. Using Dex to 'jump' should be like watching Jackie Chan get around, over, and up walls gaps etc. He needs multiple things to work around because the distance is too far for him to Athletics(Str) his way across. At least that's how I see it.
Something like that doesn't seem possible in BG:3, most heavy duty platformers don't even manage it.
