Sort of a follow up question to this question.
In that question, the auction goes 1NT - pass - 3NT - all pass. The answers to the question point out that, by opening 1NT, declarer is saying they have ~16 HCP. Their partner, bidding 3NT in response to 1NT, indicates they have ~12 HCP.
Since there are 40 HCP total, partner should be aware that they together control ~28 of HCP. Since the first opponent has already passed, this suggests that the last opponent is likely to pass as well (even if the last opponent has all 12 of the remaining HCP, the odds should be that they can't make any contract above 1NT with only 12 HCP). Therefore, partner should be able to conclude that opponents will only be passing for the rest of the bidding, i.e., the rest of the bidding will be uncontested.
Given that, why doesn't partner raise by a smaller amount, taking advantage of the bidding room to communicate their hand more clearly with declarer? It seems like they have a lot of bidding room to do so, and opponents won't be interfering anyway. Phrased alternatively, if a bidding system suggests that you should respond to 1NT with 3NT if you're holding ~12 HCP, then it seems to be giving up percentage points because it's not making use of the forecasted bidding room.
I'm wondering why a bidding system might recommend making this bid anyway, or if there's some flaw in the above analysis.