I'm going to make the case that it's actually the opposite. Rails might seem simpler out of the box, but this is all surface level. Rails is massive and extremely complex, especially its ORM, which encourages really bad database practices in my experience. And it doesn't have strong typing.
If you went head-to-head with Rails on a slightly complex project with say shadcn/ui, Convex DB, and TanStack Start, I guarantee you, the TypeScript app will be much simpler and give you more power than Rails, especially when building the UI. And to top it off, you will have strong typing everywhere -- from the DB schema to the URL routes.
And bonus, deployment is simple. ConvexDB already takes care of the backend and the frontend could be deployed to something like Cloudflare Pages.
Why would you not be able to build a "web analytics tool" with what parent comment mentioned? At the end of the day it is just data and if you are just starting out pretty much anything will scale and if you already have millions of customers you also have capital and people to think about how to make some homegrown solution to specifically cater to that.
The market for these new breed of frameworks is not huge companies with crazy scaling needs but freelancers and your very early stage startups who haven't even found a product market fit since they are starting new they don't have anything to loose with newer stuff and chances are that newer stuff also helps them do more quickly like I haven't used convex but on it's marketing page it does mention a lot and same for other frameworks like pocketbase or SvelteKit combined with a db etc. Like always there is no silver bullet and every stack can seem "random"
If you went head-to-head with Rails on a slightly complex project with say shadcn/ui, Convex DB, and TanStack Start, I guarantee you, the TypeScript app will be much simpler and give you more power than Rails, especially when building the UI. And to top it off, you will have strong typing everywhere -- from the DB schema to the URL routes.
And bonus, deployment is simple. ConvexDB already takes care of the backend and the frontend could be deployed to something like Cloudflare Pages.