Why do modpack creators never make ender dragon and wither strong?

Every RPG modpack I see always ignores the ender Dragon and Wither and always buffs bosses from generic mods, or makes a custom boss for the super generic modpack. But they never add mods that make the Wither or Ender Dragon stronger, and they do this on purpose since we currently have very good mods for that, such as Wither reincarnated, Ender trigon, Savage ender Dragon, True Ending and others. If you combine these last 3 mods that I mentioned, the Ender Dragon looks like a final Boss of Hollow Knight, it's super mega difficult to kill but it's fun, but I never understood why modpack creators never add these mods

https://redd.it/1owzwgh
@MinecraftModded

They are not ready for modded
https://redd.it/1ox2p7m
@MinecraftModded

Yeah this may be the beginning of the slopification
https://redd.it/1ox4kaw
@MinecraftModded

Wow, GTNH sure is realistic!
https://redd.it/1ox6n6t
@MinecraftModded

Lycanites and Parasites as well
https://redd.it/1ox6izb
@MinecraftModded

Behold! My transportation pipe gore!
https://redd.it/1ox72m1
@MinecraftModded

Houses I built using the mod - Cocricot

https://redd.it/1oxbmb7
@MinecraftModded