The problems with Chernobyl go way past that. Here are a few:
1. Positive void coefficient of reactivity. Once bubbles started forming in the reactor coolant, it sped up the reaction, causing a positive feedback loop. This is, of course, not the case with light water reactors.
2. The SCRAM rods actually sped up the reaction because of their graphite tips. There's a pretty crazy design defect.
3. It was physically possible for those morons to disable the safety systems.
Compare this with a truly modern design like China's HTR-DB modular pebble bed reactors, and the difference is striking. The HTR-DB has a strong negative temperature coefficient of reactivity, so all the feedback loops are very negative. They can actually shut off the cooling systems and the reactor will simply shut off because it's not able to sustain a reaction without active cooling. Overheating inherently kills the reaction. Nice, isn't it?