"Leaves more for those who do want one"
I think the passes are unlimited; my not buying one doesn't leave more for you. But why, considering what Eurail is now offering, would you want one?
A while back, a frequent poster on this board observed that, while a European rail pass used to be a no-brainer, it's no longer the bargain it once was. And that observation was made when Eurail was still offering their "Select pass", a lower cost pass for a few contiguous counties. With the demise of the Select Pass, a Eurail pass has ceased to be a viable option for most travelers.
What does Rick Steves say about rail passes. "The more time you expect to spend on the train, the more likely you'll want a pass" and "The more countries you plan to visit, the more probable it is that you'll save money with a pass." I don't think most people spend enough time (or should) on a train, or visit enough countries, to warrant a Global pass. Why should you have to buy a 33 country pass if you are only going to visit, say, eight countries, or a 15 day pass if you are only going to use ten days?
Twenty years ago is returned to Europe after a decade of not going, and, out of habit, I bought a rail pass. When I came home, I looked at where I had gone and, even then, not knowing what I know now about how to save money on tickets, I concluded that I had just about broken even with a pass. Since then, before every trip, I have costed out the rail trips I plan to take, and compared that to the cost of a rail pass, and a rail pass has never made sense.
Looking at my most recent trip, where is used rail on eight out of the 21 days I was in Germany - six changes of venue, including an almost day long trip from St Goar to near Füssen, plus two side trips. At today's fares, I would have spent 257€, about $323 for two adults. That consisted of one day long, advance purchase, SparPreis ticket from St Goar to near Füssen, three regional passes, 2 local passes, and two point-point tickets. All but the SparPreis ticket were purchased on the day of travel.
Eurail does not have an eight day pass - the next pass up after 7 days is 15 days, definitely overkill. Compare the 7 most expensive days of my travel, which cost us $296, with the current 20% discount price of a 2 adult Eurail Global pass at $660. We would have gotten the price for 2 seniors, which is only $596, still over twice what I spent.
But whatever, don't just blindly buy a pass 'cause you can use it on your phone. Compare; do the numbers. And to find the best ticket prices, you might want to ask people here.