What are the advantages of modern js framework in Rails instead of assets pipeline?

Question

Ruby on Rails

There is a big project on Rails that has been running for several years. Right now the front part uses bootstrap+jquery+some_external_js_libraries. Everything works as standard, through the assets pipeline.
It's time to optimize the front part. Along the way, I decided to switch to foundation and a little later I thought about react || vue || ember.
If you switch to them, then here's what I have to do (as I understand it):
1. Choose the right framework (waste time)
2. Learn it (waste time and effort)
3. Implement it in rails instead of the current template system (takes time + in the future it will only be more difficult to finish something)
Against the background of such resource costs, rendering on the client side does not seem like a big plus.
Actually, the question I have already voiced.

Answer 1

for assets
pixelatedworks.com/articles/replacing-the-rails-as...
for client-side templates there is no universal solution, sometimes slim is convenient, sometimes jade is convenient.