As long as my mastery is fine, jungling should be accessable to the champions able to do it without being destroyed by the jungle mobs. It's hard gated so hard because of how expensive runes are. It's pretty harmful to the game actually.
I should be able to clear a jungle camp at top efficiency.
To offer a counterpoint, you can't do *any* role at peak efficiency without the appropriate runes.
Consider the Support without GP10 runes or the Top laner without armor runes; neither of them is operating at peak efficiency. Why would Jungle be a special case?
Now, there's a whole 'nother conversation to be had about Runes (one that's admittedly way above my pay grade, as I'm not a designer), but I don't think it's really fair to expect one role out of five to be exempt from the need for runes to be 100% effective.