No no not dumb at all. There are certain conditions that have to be met in order to score a point. Generally scores weren't awarded because uke (attacker in tanto randori) didn't land a clean strike (arm fully extended, moving forward).
In Tanto Randori the only legal tanto strikes involved fully (or near fully) extended arms moving forward. In other words, a basic thrusting motion (though slight variations of this were allowed, see below). Slices wouldn't get you any points. Tanto Randori was a game based on traditional Aikido movements, it wasn't ever meant to replicate a knife fight or anything.
These are from a PDF I had access to (not to sure how up to date they are) regarding more detailed descriptions of criteria for scoring:
1 Specific conditions:
a. The rubber knife must land in the part of the opponent’s body between armpit and belt
levels. This includes the front, back, and both sides of the body, as well as the upper arms.
However, the belt itself is not included in the target area.
b. Tanto must step in and stab with his back straight and his balance stable.
c. The rubber knife must touch the opponent’s body at an approximately 90-degree angle. But
this particular condition does not have to be satisfied when Toshu is either off balance, has
assumed an undesirable posture, or has already fallen on the mat.
d. Rubber-knife stabbing should never endanger the safety of the opponent. Particularly, the
type of stabbing with the fist landing directly on the opponent’s body is subject to
penalization. However, if Toshu comes in without proper taisabaki, it is considered to be his
2 Tanto is allowed to stab the opponent’s flank by swinging his tanto from the outside
(“Mawashi-tsuki”) as long as all the conditions in #1 are satisfied.
3 Tanto is allowed to stab the fallen opponent once right after the latter has fallen as long as
all the conditions in #1 are satisfied.
4 When Tanto scores a tsukiari point at the same time that Toshu scores a yuko or greater
point in techniques, then the tsukiari point will take precedence over the toshu technique.
B. Inadequate (ineffective) or invalid stabbing
1. Tanto techniques that do not satisfy the above conditions will not be counted as effective
2. Tanto techniques will also be regarded as invalid unless the tip of the rubber knife has
clearly touched Toshu’s body and Tanto has stabbed with proper foot movement.
"Let your food be your medicine, and your medicine be your food"