Do you find that your team often has to reinvent the wheel in terms of what libraries like React/Vue/Svelte have to offer? Doesn't that increase time and scope tremendously?
I actually find that I often have to reinvent a lot of the browser's wheel when using React and friends, so it's often a wash.
Complete back button support beyond what the router offers, saving search/sort/filter in query string so users can copy/paste/bookmark/back/forward, handling connection and other errors gracefully, loading, accessibility, having to wrap Vanilla JS components into their own framework-compatible components, having to update things in different parts of the screen. And the last often requires a total paradigm change in terms of how data is handled in the app thanks to the introduction of state managers (React-sans-Redux looks totally different from regular React). All those require extra work on every project I worked, and no, libraries often don't solve them completely or as easily as it is with previous backend tech.
These frameworks are also steering a lot of software into some very problematic product decisions. Like using fancy third party components where stylized native would suffice (and be more useable/accessible), using date pickers for absolutely everything that looks like a date (it sucks to type your birthday in those unless you were born this month), saving things in the browser instead of in the backend (so the site looks different in different computers), or just having some specific UI-framework forced on you so you have to use a certain framework.
There are obvious advantages to frontend frameworks, and I'm a big fan of React/Vue/Svelte. I really like those things, been using those for years and I was doing what used to be called "DHTML" since the late 90s. But it takes so much more complexity than the average web app to reap those advantages... IMO they are definitely overused.
Vue.js has led the way on HTML first in a lot of ways. You can pull it in with no build step, you can add dynamic content to pages without making it a SPA, and it mostly works through overloading HTML attributes for basic use cases.
