Every webapp built with something other than GraphQL ends up with an ad hoc, informally-specified, bug-ridden, slow implementation of half of GraphQL. Yes, a book tracking app absolutely needs GraphQL.
Do you need a separate frontend framework? No, probably not, and that's exactly the problem that Next solves - write your backend and frontend in the same place.
Do you need a complicated build process? No. You want your build process to be just "run npm". And that's what something like Next gets you.
"Monolithic RoR app with HTML templates on VPS" would introduce more problems than it solves. If Next-style frameworks had come first, you would be posting about how RoR is a solution in search of a problem that solves nothing and just overcomplicates everything. And you'd be right.
Do you need a separate frontend framework? No, probably not, and that's exactly the problem that Next solves - write your backend and frontend in the same place.
Do you need a complicated build process? No. You want your build process to be just "run npm". And that's what something like Next gets you.
"Monolithic RoR app with HTML templates on VPS" would introduce more problems than it solves. If Next-style frameworks had come first, you would be posting about how RoR is a solution in search of a problem that solves nothing and just overcomplicates everything. And you'd be right.