Smite in particular is very deliberately locked behind a level barrier; jungling is difficult enough that new players are not expected to cope with it. New players do not have runes or the knowledge needed to jungle sustainably, let alone effectively, and there's plenty of other things for them to be learning. So Smite is locked away to avoid drowning new players in even more strategy and gameplay mechanics.
Flash adds so much to the game that it sorta falls under the same category.
Ignite, not so much. Point, click, damage, done. Not sure why that one is locked away.
https://i.imgur.com/1HvNiEO.png?noredirect