Query about puzzle 71873

Puzzle:

lichess.org/training/71873

Could someone please explain the computer's solution here? After 17 Rxf6 (RxB) why not g7xf6 (g7xR), in which case white has lost the exchange? There is no immediate mate as black has a tempo to block the bishop with f5. Is it because white eventually wins by bringing in the remaining rook? That's not the usual kind of puzzle solution: white loses material but gains a strategic advantage.

According to my Stockfish, after gxf6 Qxh6 f5 Rf1, Blacks's 5 best moves are, in descending order:
Qd6 (mate in 17) Bxf5 exf5 Qxd6
Rfd8 (mate in 11) Rf1-f4 f6 Qg6
Rfc8 (mate in 10) Rf1-f4 f6 Rf4-h4
Rf8-b8 (mate in 9) Rf1-f4 Qd7 Qg5
Qd7 (mate in 9) Qg5 Kh8 Qf6

So stockfish agrees with me ;-)

I guess the computer selects puzzles by selecting blunders - including blunders of omission where one missed an opportunity - and it assigns blunder status to losses or missed gains that are substantial. I further guess that in this case - rarely - it assigned blunder status to a missed opportunity neither for immediate mate nor material advantage (there is actually material loss) but a strategic advantage so substantial that there is almost certain mate in 9 or 10 moves.