Apologies for calling you a troll, but here's the thing about unlockable difficulties:
Do you care about it in Doom 2016 where Ultra-Nightmare difficulty requires you to beat the game in Nightmare mode?
Do you care about it in Resident Evil 4 (both) where Professional difficulty required you to beat the game in Normal mode?
Do you care about it in Metal Gear Solid 2 where Extreme difficulty required you to beat the game in Normal mode?
Do you care about it in Soul Calibur 6 where where Legendary difficulty required you to beat the game in Very Hard with a Gold Rating?
Do you care about it in Cuphead where Expert Difficulty required you to beat the game in its Normal mode?
Do you care about it in Dead Space where Impossible difficulty requires you to beat the game in its Normal mode?
Do you care about it in Metroid Prime 3: Corruption where Hypernode requires you to beat the game in the Normal setting?
Do you care about it in Diddy Kong Racing where Adventure 2 requires you to beat the Adventure mode?
Do you care about it in StarFox 64 where Expert difficulty required you to beat all stages of the normal mode with a medal?
Do you care about it in Megaman Zero where all of them require you to find collectibles to unlock Ultimate difficulty?
Do you care about it in Diablo 3 where Master Difficulty requires you to beat the game once, and then Torment difficulty which requires one of your characters to reach level 60?
Do you care about it in Pokemon Black 2 where Challenge mode requires you to beat the game once?
Do you care about it in Mass Effect where Hardcore Difficulty requires you yo beat the game once, and then Insanity difficulty requires you to beat Hardcore mode?
Do you care about it in KH 3D Dream Drop Distance where Critical mode requires you to beat the game once?
Do you care about it in Bayonetta where Hard difficulty requires you to beat the game once?
Do you care about it in GoldenEye 64 where 007 difficulty requires you to beat every mission in 00 difficulty to?
Difficulty modes being locked behind completing a game for the first time is a feature that has been part of gaming for decades. It encourages replayability and in many cases changes how the whole game feels. I believe you're trolling because anyone that has been gaming for the last 10 - 30 years understands the value behind unlockable difficulties. If you're not trolling and you're serious, then I'm a bit baffled about such a closed mind about game design, but if that's the case, then you're entitled to your opinion, and I then hope you mean all games and not just XVI because CBU3 made it and you're angry at them for whatever reason.
*Edit: Making Normal Mode more challenging is reasonable. I can get behind that, but it has nothing to do with unlockable difficulties.