How does this HTML block the auto insertion of my email address from chrome?

At first I thought it was some jerk move to make me type my username for added "security" on top of 2FA so I decided to fix it with tampermonkey and remove the autocomplete="off" attribute only to discover that there wasn't one.

Why does Chrome not offer to autofill the email input in this form? This is a link to the site.. But this is the form that is blocking autocomplete on the email address.

<form method="post" class="form-horizontal">
  <h1 class="paste-page-header">Log in</h1>
  <div class="form-group">
    <div class="col-md-24">
      <label class="paste-input-label">Email</label>
      <div class="paste-input-wrapper">
        <input type="text" id="email" name="email" placeholder="Email" tabindex="1" required="true" class="paste-input sl_whiteout" autofocus="autofocus" maxlength="255">
      </div>
    </div>
  </div>
  <div class="form-group col-md-24">
    <button role="login-button" type="submit" tabindex="2" class="paste-primary-button" data-loading-text="<i class='icon icon-spinner icon-spin'></i>" value="Log in">Next
    </button>
  </div>
  <span class="paste-text">Don’t have an account yet? <a href="/try-twilio?g=%2Fconsole%2Fsms%2Fdashboard%3F&amp;t=182b71c36e3bb0a0a788ab671fbe875c7b46602de5f49fb3e441645b8848a76a" class="paste-link" tabindex="3">Sign up for free.</a></span>
  <input inert="" readonly="true" type="password" id="password" name="password" tabindex="50" style="opacity: 0.02;" aria-label="This is a hidden password field for compatibility with password managers. Please ignore this field.">
  <input type="hidden" name="g" value="/console/sms/dashboard?" class="sl_whiteout">
  <input type="hidden" name="t" value="182b71c36e3bb0a0a788ab671fbe875c7b46602de5f49fb3e441645b8848a76a" class="sl_whiteout">
  <input type="hidden" name="CSRF" value="2869689c41323f2456ec6558c8ee7f3e4c409eda3bbed69bf10228f752a293e4" class="sl_whiteout">
</form>

After you type your email address, it will allow you to autocomplete the password, it's just this field that is a problem. And I tried this:

> x = document.getElementById('email')
<input type=​"text" id=​"email" name=​"email" placeholder=​"Email" tabindex=​"1" required=​"true" class=​"paste-input sl_whiteout" autofocus=​"autofocus" maxlength=​"255">​
> x = document.getElementById('email')
x.autocomplete
''

So, they aren't disabling it with JS (at least not in any way that I can see.....

I'm asking so that I don't make this mistake on any of my sites and because I'm really curious how they pulled this off.