So what if it violates an RFC, what harm does it do if you implement your own status codes? Controversial and unpopular opinion, but RFC specs went out the win

So what if it violates an RFC, what harm does it do if you implement your own status codes? Controversial and unpopular opinion, but RFC specs went out the window as soon as SPA apps came about. If I can't use my back button without my page being hijacked to the home page of the site then to me RFCs are now just a defunct recommendation.