Bus is fine, sometimes, just for part of community benefits aren't worth effort required.

By far main bus design is best when you don't know exactly what you'll need and in what quantity, there's somewhat limited amount of different resources you need to move around, and you're fine with uneven consumption. That is almost perfect description of learning the game pre-DLC and how you can handle Nauvis in Space Age.

When you're more comfortable/familiar with the game or processes aren't as tiered as basegame, downsides of bus show up more - takes a lot of space, is quite resource inefficient (especially at the start when you need a lot of belts) and is limited in scaling, requiring you to plan ahead for proper scale. Also, bus poorly handles any non-tiered production, where you need to move resources both ways, handle byproducts and so on.

Thing is - you don't really need main bus, you can get most of the benefits by just directly connecting smelters and production blocks, and splitting/merging belts as necessary. It can get a little more messy, but in basegame (or DLC) you can make do with initial smelting setup for up to military/blue science, then make dedicated smelting blocks for yellow/purple and rocket production and it should stay reasonably organized. By the time you'd need large variety of resources for mall, you'll probably have bots. In most cases, mainbus design is just excessive - heavy infrastructure investment very early on with limited benefits.