I don't see why miles and points should be any different, they did not have laptops in those days too, so are they out of the question? It matters not what the item is, rather what category they fall under. If they are to be considered as a physical gift - not cash, than only if you hold Ma'aser is necessary on non-cash item will miles be be subject too
Yes they didn't have laptops, but as you yourself write, it is clear which category they belong to.
The point is that it is not clear which category miles and membership points belong to, which raises the
possibility (and I emphasize that word) that they are in a category of their own; not quite cash, not quite Mitaltlin.
If that is the case, now that you finally admit that
most Poskim hold that Maaser Kesofim is a Minhag, then why should the Minhag apply to miles? It think it is fair to say that from the time that frequent flyer miles were "invented" (according to Wikipedia, in 1979), most Frumme Yidden have not been separating Maaser from them, meaning that there is no such Minhag!
I also want to emphasize (in case it was not obvious from my first post) that my goal is not to "pasken" that Maaser does need not to be separated from miles (as if my opinion would matter...). I am just bringing up the issues that I have with this.