Building good onboarding is not easy and it's quite tedious work. It's also extremely important work that is frequently ignored because of how tedious and thankless it is. Why is it important? Onboarding is the single place in a product that every user is guaranteed to experience at least once. Small changes to onboarding can have effects on user retention like the proverbial butterfly flapping its wings and causing a hurricane.
I'm not surprised an app with no profit motive behind it doesn't focus on this kind of work. It's very hard to motivate yourself to do it if it's not your job.
But in the scope of an open source project user retention is not always the most important thing.
One could argue that pre-2010 Twitter itself is proof that not having the slickest onboarding path is not something that will prevent success. Onboarding can be improved and reinforced over time. Infrastructure is much more complex and building it first prevents a fake-it-until-you-make-it mindset.
I'm not surprised an app with no profit motive behind it doesn't focus on this kind of work. It's very hard to motivate yourself to do it if it's not your job.