The OP mentioned the fumble cost the team, if that's the case then any error could be deemed costly.
Unlike Dak, Hurts made up for his error, which included a 75 yard drive for a TD and 2 pt, with less than 6 min to go....that's the difference, one comes back from his error whereas after the second INT vrs 9ers Dak capitulated.
This has zero to do with Dak.
If any player fumbles into a fumble-6 it is VERY costly. In a game decided with seconds left it is obviously more critical.
Hurts was really good all day but that play was insanely costly. With the way Hurts played had he not fumbled that into a Chiefs TD, the game would have literally been over at halftime.
The Chiefs only had a handful of 2nd half possessions.
If Dak was QBing that Eagles team yesterday they probably win by 10.
Outside QB and TE I am not sure the Chiefs had an advantage in any other position on the field.
Hurts is a good player but anyone who actually watches QBs saw limitations yesterday.