And what is the "incentive" to do that? Does it unlock more special powers, more interesting dialogue, does it make it a whit easier to defeat Alduin or anyone else for that matter? No, no, and no.
There isn't even a Steam achievement for it. In short, there's not a hint of evidence that the idea ever crossed anyone's mind.
Point of fact, it's perfectly possible to get to that wall without entering the tomb at all.Like, the Greybeards can and will tell you a location you physically can't go to to find a Word Wall. If they send you to find the word of Animal Allegiance tha'ts hidden away in Ysgramor's tomb, you're only getting rid of that quest marker if you don't do the Companions questline far enough to get full access to the tomb.
If "an NPC told me to do it" constitutes the game instructing me, then it also "instructs" me to join both factions in the civil war, help Madenach bust out of jail, and kill Paarthunax. Are those "canon" too?Likewise, the game instructs you to do certain things that would result in you joining a faction.