title: Why does react make input[type="text"] fields readonly unless I supply onChange callback?
body: <p>Initially I had: </p>
  
  <pre><code>&lt;input type="text"id="requested" name="requested" ref="requested"   /&gt;
  </code></pre>
  
  <p>which was <em>readonly</em>. </p>
  
  <p>changing it to:</p>
  
  <pre><code>&lt;input type="text" onChange={function() {}} id="requested" name="requested" ref="requested" /&gt;
  </code></pre>
  
  <p>made it accept input from keyboard. Why does this happen?</p>