That is a terribly user-unfriendly design decision because it does not distinguish between failure modes. Maybe your site is broken because I am running noscript or maybe it broken because it is mis-configured or recently hacked or my ISP's proxy is black-holing things or a dozen other things that could go wrong.

The point is that it is relatively trivial for the developer to add automated checks for per-requisites and display warnings for the ones that are missing. It is a lot harder for each user to manually run down through the list of all the things that could go wrong.

If they are missing, tell me your site needs javascript or cookies to operate and I might enable them for your site and give it another shot. But if I just get a catastrophic failure without explanation then I'll probably hit "back" and pick another similar site out of the google search results that brought me there.

Just don't make the warnings into roadblocks. Inform the user and let them decide to proceed or not.