Puzzle issue?

New to Shogi and just a beginner really. This puzzle: #VhCKr (rated 1755) appears to have a flaw.

The solution is:
1. P*14
2. Kx14
3. N*26
4. K-13
5. L*14#

I agree with this...but why can't I drop a pawn on 14 (i.e. 5. P*14#)? I was able to drop it at the start of the puzzle, so what has changed to stop me dropping it at the end?

Oh my, sorry! Showing my ignorance of the Shogi rules, which are to be fair somewhat intricate.

After re-reading en.wikipedia.org/wiki/Shogi, I see that dropping a pawn on 14 would result in immediate checkmate, violating the "Drop Pawn Mate (Japanese: 打ち歩詰め uchifudzume)" rule.

Hadn't realised you were not allowed to checkmate with a pawn drop. Seems a weird restriction...is there a reason why Shogi does not allow a dropped pawn checkmate?

2

Too powerful, I guess they had to nerf pawns a bit.

1

I heard that it was originally a restriction in tsume, presumably because it allowed for more interesting constructions, and was later applied to the main game.

2