Earlier quoted context omitted.
You simply trade back-end frameworks complexities for the front-end framework complexities. With the right architecture there is no huge difference IMO, just of course you also need to upgrade your teams so that they can handle a lot more tasks on the front-end than with SSRs (and you'll probably need less back-end devs)
Front-end frameworks have a way of going in and out of fashion / support much faster than backend ones.
FE is a vibrant ecosystem and the tooling, in my opinion, is some of the best I have worked with as a SE.