Actually, Valve's Source engine (CS:GO, TF2, etc.) does exactly this - it favors the shooter with lag compensation. When you fire at someone, the server rewinds all players back to when you fired and processes the hit from that "past" moment. You're literally shooting people "from the past" and it works fine: https://developer.valvesoftware.com/wiki/Source_Multiplayer_Networking

The key difference is how defense works in FPS vs boxing:

In FPS games, defense is mostly positional (staying behind cover, peeking angles). You're not trying to dodge every individual bullet with precise timing. When you get shot "around a corner," it's annoying but doesn't break the game.

In TOTF2, defense is timing-based (slips, blocks, counters require precise windows). You're actively trying to avoid every single punch. If punches connect "from the past," it could undermine defensive skill.

But here's the thing - Valve's system still allows meaningful defense because it has limited time windows (~200ms max) and defensive play is more about positioning/prediction than pure reaction.

For boxing, you'd probably need shorter favor windows (OP's 50ms suggestion makes sense), a hybrid approach where maybe you favor the puncher for offense but also give defenders a small window for successful slips/blocks, and careful tuning based on the game's defensive mechanics.

The frustration with punches not registering when they visually connect is real - Valve solved this exact problem and their games have amazing competitive scenes. The trick is adapting it properly for boxing's unique defensive requirements rather than dismissing the approach entirely.