Or perhaps there was this MASSIVE fucking Tsunami that killed 10,000+ people and a massive earthquake.
I think you might have forgotten about having a massive amount of sea water pouring into the facility. Roads into and out of the area destroyed. Emergency services essentially crippled.
None of which affect a reactor installation operated properly with suitable systems to mitigate basis design issues. Everything you have pointed out was covered by the official report into the disaster and the findings were that it was a "Man Made" disaster.
You take out the generators and the grid tie and even IF that could melt down the facility (note it would be unlikely as you would have to have the same era and plant design as Fukushima) there would be 100 generators and people on site within hours in any other circumstance outside of a massive earthquake and a killer Tsunami.
No, it has nothing to do with the generation of reactor, but the type of basis design issues and unfortunately generators don't counter the NRC scenarios for intentional sabotage.