It is probably worth saying that almost no-one actually does this in the modern era. Unless you’re trying to lose yourself in the vastness of space where civilization can’t find you, all you’re doing is playing the game on extra-hard mode. And you don’t even get an achievement for it.
Logistics, like @Scott_Kenny said. Bear in mind that the reason the rocket equation is so gosh-darn tyrannous is that basically every other factor in logistics is screaming “go big or… no, just go big”. There’s a reason container ships have consistently trended upward in size with the technology available to build 'em (pace the ability to fit through bottlenecks like Panama and Suez), which mostly means engine size.
Likewise, in the 'verse, megafreighters have largely trended upwards in size with the ability of the vector-control core to apply its rocket-equation cheat codes to them, and this is but one more application of that principle.
Also, I mean, these days even colonists are a little spoiled. Sure, there’s some nostalgic, retro fun in camping out in inflatable polymol cabins and hand-welding the family fusion reactor together before the power cells on the xaser torch run down, but it’s the kind of thing that’s fun for a week, not a lifestyle.
(So you drop a city from the sky instead. Ah, modernity!)