This site gives me an interface to say, "oh yeah, I /do/ need VLC on this laptop, come to think of it", rather than having to lazy-evaluate that when I have a video downloaded and realize I don't currently have a means of playing it.
I spend a fair bit of time doing DevOps work, and this isn't meant to be some sort of configuration management or provisioning tool. This is for desktop / dev users, which is, I think, quite a different use case (but an increasingly relevant one). I have a dotfiles repo, which is to say I'm familiar with the "document things in scripts and repos" game - but it's not clear to me that something like a script-as-documentation is even a useful process to go through when any given computer I set up is going to be used differently. That laptop playing VLC is very different than the web dev box I spin up to mess around with a new project.
The motivation was basically a version of ninite[1] for Linux. So very desktop-focused. I actually got in touch with the ninite folks, who used to run a Linux installer [2]. They said there wasn't enough interest and package managers are "good enough." I respectfully disagree on that point - I think that having the ability to point-and-click for the core, most important packages you want to install is really useful when you're spinning up a new desktop from scratch.
I was running into this problem after basically doing ad-hoc setup for every new machine I turned on. Sure - I could write a shell script / list of packages and save it to my dotfiles repo, but where would the fun be in that? :)
(Plus, package lists on every machine are different)