There are a few free packages (Active Admin, administrate, rails admin) built a few years ago that can help you build a CRUD UI, but the conversations I had with developers is that they are a bit annoyed with them.
I built Avo as a modern alternative learning from the past products and improving on them.
Why do you say that? Start-ups by definition need to move fast and test out hypothesis. With a tool like Avo you could prototype something, get it out to your customers and get feedback fast.
The secodn use-case is internal tooling. When I worked at a start-up we had a lot of "shady" internal tools built fast, crappy and unreliable (because it's just an internal tool) and we always had issues working with them.
I build a lot of internal tooling using Avo and the process is quite painless.
I built Avo as a modern alternative learning from the past products and improving on them.