Rails is a fully formed opinion on how you should write a web app in Ruby and all the various technical components you need to fully realize that opinion.
Tailwind is a fully formed opinion on how to use CSS (utility classes etc.) and all the various technical components you need to fully realize that opinion.
Thinking of Tailwind as just a bunch of regular CSS utility components is misunderstanding the scope of the project. That alone has a lot of tradeoffs and compromises - the file size is absurd and you can't bundle things into components, you also can't have arbitrary values in the utility classes. It wouldn't be a complete opinion on 'the best way to use utility classes', or however you want to frame Tailwind.
Tailwind is a fully formed opinion on how to use CSS (utility classes etc.) and all the various technical components you need to fully realize that opinion.
Thinking of Tailwind as just a bunch of regular CSS utility components is misunderstanding the scope of the project. That alone has a lot of tradeoffs and compromises - the file size is absurd and you can't bundle things into components, you also can't have arbitrary values in the utility classes. It wouldn't be a complete opinion on 'the best way to use utility classes', or however you want to frame Tailwind.