Something is standing in the doorway. You were going to walk through, and now you are not. The word never names the thing that blocks you in the same breath as the blocking: sometimes it is a rule, sometimes a number on a price tag, sometimes a rival so far ahead that the other results cannot get past. In every case prohibitive describes the blocker, not the person turned away, and it says the door is closed rather than merely heavy.
From the word’s history
The source analyses the word as prohibit + -ive, where -ive names a tendency, giving 'tending to prohibit'. That is exactly the blocking picture. The source does not gloss the older Latin form, so nothing beyond this layer is claimed here.
資料把這個字拆成 prohibit 加 -ive，-ive 表示「傾向於做某件事的」，合起來是「會去禁止的」。這正好就是擋在門口的畫面。再往前的拉丁文，資料沒有給解釋，所以這裡不多說。
packet Wiktionary etymology_text for prohibitive: 'By surface analysis, prohibit + -ive'; kaikki:3f6f69a190036ae4
登入就可以看每一支怎麼連回核心畫面。