Everyone who makes this argument seems to be plainly ignoring a good half of the address spec, that Urbit's 32-bit namespace is part of a total 128-bit address

Everyone who makes this argument seems to be plainly ignoring a good half of the address spec, that Urbit's 32-bit namespace is part of a total 128-bit address space. If I told you that IPv6 has 32 of its 128 address bits reserved as markers for making top-level subnets out of them (this is not true, but for argument's sake, pretend it was) would you say "Oh no, there's not enough IPv6 for everyone to have their own subnets" ? Of course you wouldn't, because addresses are 128 bits long and there's enough address space for "EVERY ATOM ON THE SURFACE OF THE EARTH, and still have enough addresses left to do another 100+ earths." per the first StackOverflow post I could find on the subject. Is there enough address space for every atom on the surface of the earth to be neatly organized into subnets according to ownership rights? Well that's debatable, and if you want to compare apples to apples, you should ask that question. If Urbit runs out of planets, then it will have roundly surpassed the expectations of anyone who makes this argument. You don't solve these problems on Day 1, it's really enough to have a plan that would allow 20-50% of people on the planet to have a stake in ownership of Urbit at this stage. When it starts getting cramped, how about THEN we spend some time and tackle scaling past a usership base of 50% of the population of humans that are alive? There was actually a point to the scarcity, it's meant to solve the spam problem. "Planet" identities are meant to be precious. If your identity was worth $10, you probably wouldn't use it to engage in spamming unless you were sure that you could get more than $10 from the campaign before landing your address on a blackhole list. (And if it was possible to reliably achieve a profit like this, it would undoubtedly drive the price of a planet up, as others figured out how to compete with you at doing that.) And even that is a naive assessment of the scope of the idea and how it prevents spamming. The identities are provisioned in a hierarchical fashion, such that if you landed more than a couple of planets on such a spam list (none exists today, but...), you would probably find out pretty quickly that nobody with inventory is willing to sell you another one. (Lest they wind up getting their whole "star system" banned from polite society for association with spammers.)