The age thing
I think age has nothing to do with what's in one's heart !
We ( mate & I) have been truly "poly" since young teens ! This is no reference to sexuality either, even though the expression of that lovestyle has been open to sex as much as anything.
We discovered early that love and connection have no theoretical limits.
The concern we might have about age - which is in reality more about experience and culture than a number - is probably that "trying on of hats" you speak of. When we are young we have a natural desire to get out there and experience life and often times we don't do much homework in preparation for that. Just jump in, assume our invincibility and go for it !
We've also seen, and experienced, a wider population getting wind of something that looked promising, wanting to climb on the bandwagon, but in the process bring all their baggage, negativity, bad habits and ethics with them. Big alarm bells there. Natural skepticism here. Have seen whole promising cultures destroyed from within from infiltration of undesirables.
With youth, the lack of experience and inability to see how those factors play in and how to spot them a mile off and take the necessary detour is one of the risks. Study, consultation with those more experienced and knowledgeable is imperative. The old saying about "those who refuse to learn from history are doomed to repeat it" has a lot of validity. Translating to "those who are unwilling to listen and do the necessary work" are a danger not to be ignored.
This has NOTHING to do with AGE !
It's all about an attitude. If you seek a better way, there are those in the world that honor and support that. If you are just an infiltrator, looking to reap the benefits with none of the effort, then you need to find another world.
If that makes sense.