First, "same code on the client and the serve" is wrong. Since when do RSC's run on both the client and the server?
Also, you honestly believe that wanting to use the same language across paradigms is a "coding bootcamp" thing lol? That something like Blazor was born out of a coding bootcamp?
Have you ever built a web app? Both front and back end? Have you ever had to deal with the tension of duplicating code? Models, validation, ideas?
If you answered yes to those questions but still don't see how de-duplicating code like that can be important, than I'm 100% positive you're still in the boot camp.