While one can indeed sometimes connect to one certain chakra to draw on what it represents and has an influence over, Tadashi is correct when it comes to the idea of expanding or otherwise working to enhance or grow their potential.
Throwing open your crown, focusing entirely on spiritual attention and growth while neglecting the other chakras would be like building the roof of a house without any walls or foundation. Sure you might have a very nice, fancy roof but it would just be sitting on the ground. The same goes for other chakras; The third eye might provide intuition and observation but then what? You see, but what can you do with it? You purify and expand the throat, learning to express and .anifest but how do you use it wisely and in a any that doesn't become self-destructive? What about the heart? Love without control or boundaries becomes blind and abused. Solar plexus can become directionless energy without focus or efficiency. Groin can become obsession and addiction. Root, selfishness and disconnection.
The chakras and other facets of our incorporial Selves are a -system-. They work together, interconnect, and have influence over eachother along with ourselves. And it is easy to see the results in the people around you. Reflected in all those extremists in society loudly pushing for one thing or another. Survivalist touting the need to live off-grid. The paranoid raging against the 'big brother' or some other inane conspiracy. Granola-munching super-spiritualists who run around preaching soul while living unbathed and riddled with disease and drugs. All high vibration and rotted teeth.
Any structure built with all the weight at the top will surely fall over. And there have been sayings and recognitions around for literal millennia showcasing that recognition. From the Roman golden means and confuscian 'Fetch wood, carry water. Gain enlightenment. Fetch wood, carry water.' to more modern sayings such as 'One foot in the ocean, one on land' or 'have your head in the clouds, but keep your feet on the ground.'
Harness or amplify in the moment as needed, sure. But develop together. It avoids many pitfalls a person can get trapped in. While people can (and likely have) focused on one to the detriment of others, it just reveals the risks and traps of such an imbalance time and again. I don't like watching people getting trapped in cycles or having their path and process collapse over and over, forcing them through one crisis after another until they regain balance or give up entirely. Too many people already do too many foolish things because of being so wildly off-balance.