I repeat, you can tell any stories from the Adventurer difficulty level, this will in no way change the fact that these perks are worthless
Although I don't play on adventure difficulty level, stories from perks being useful on adventurer difficulty are 100% valid.
Perk balance is not done based just on insane difficulty nightmare speed zombies. It is based on all settings.
For example, you say iron gut is a useless perk. If you watch any larger multiplayer youtube series, you will find that it is a necessity. Food is much more difficult for larger groups, and iron gut helps them a lot. See Grand Spartan multiplayer series for example.
You say no one fights with knives. Although I haven't watched him, apparently jonah birch uses knives due to the slow that you get from the perks in his insane difficulty, always run, nightmare speed, permadeath playthroughs. Maybe you can get some tips there on how it's done.
Parkour is used by lots of people who do high level melee horde builds. I have seen people who fight the horde in the streets with melee, utilizing pillars to jump onto rather than an actual base. It looks both fun and useful to me, although as a disabled grandmother i don't have the twitch reflexes to make it work for me.
For people who play on lower difficulties, who matter just as much as you, fully perking a melee weapon can make a difference in a one hit kill or not.
For people who prefer the extra challenge of playing on an all snow or all desert map, well insulated is a very useful perk.
Most of the perks you deem useless are quite likely high priority perks for some people, some situations, some difficulty level, etc.