cuz nintendo never thought for glory out completely in the first place.
They also handed little mac his best stage on a silver platter with for glory mode(not that it makes too much a difference as most macs are still pretty easy to deal with.). Nintendo just flat out didn't think things through. They listened to a dumb meme/stereotype and data from basic brawl during its lifespan, and decided that final destination *MUST* be the most neutral/fair stage in the game, as opposed to listening to input from actual competitive players.
However, just look on the bright side, projectile campers did receive a nerf overall compared to brawl. Sure we've got duck hunt, and shiek's needles to worry about. But compare that to brawl falco's laser game, pit's arrows, (
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i miss having my brawl arrows) toon link's wall of projectiles, and others from brawl where the projectiles were a lot more effective.