As I've said, it is a felt-experience, both quite personal and with a universal quality that allows us to experience something together.
I'm not sure if you see the problems here.
In order to convince anyone who is not already convinced, there are some things you need to address. To whit:
(1) If it is an udefinable, uncommunicatable felt-experience, how do you know that it is universal?
(2) If it is definable and/or communicatable, how come you are unable to define and/or communicate it so that we know what you are talking about?
EITHER what you are talking about cannot be communicated effectively, in which case it is impossible to know it is universal, OR what you are talking about can be communicated effectively, in which case it is possible for us to determine whether or not we believe it is universal for ourselves.
What you are asking us to accept is that you (and, perhaps, those who are already convinced of the same thing) have some special way of knowing that something which cannot be effectively communicated is universally felt, OR that you (and, perhaps, those who are already convinced of the same thing) have some special way of understanding which makes communication a moot point.
(This is, BTW, the reason that divination spells in rpgs aren't foolproof; even if you have access to "revealed knowledge", your claim of said access isn't necessarily sufficient to convince anyone who doesn't already believe what the spell revealed!)
Because, while the experience of "love" may be extremely personal, it is also communicatable. I communicate love, and receive communications of love, on a daily basis. To and rom family, my partner, and close friends. And, if the only way one can communicate one's love is through poetry.....well, my shelves contain much poetry on that topic.
Indeed, I have seen some attempts at defining what that core experience means to various people here on EN World, often in sig blocks, and sometimes even quite poetic. So I would say what any given person gets from D&D is certainly communicatable.
But I have seen nothing to indicate that there is a "universal" core experience that spans all editions and all playstyles, which is also at the same time particular to D&D (rather than being embedded in all rpgs).
And that is the bar you must pass, in my case at least, to convince me that your premise is viable.
RC