It never was. If we want to talk about the powerful being held to account by the international community, realise that at some point that means canvassing the idea of invading China/India/the United States/Europe when they get out of line. That isn't an option. That would potentially reduce big chunks of the world to sand and anything less can't constrain the powerful. WWII alone levelled an entire continent, and that was with primitive weaponry compared to what is available now.

Trade sanctions aren't effective at changing behaviour and it isn't obvious if they would do more good or more harm if deployed against a superpower. Note that most superpowers' economic problems were due to internal not external policy.