There's a huge difference between everything you mentioned, and dealing with 'browser quirks' like:

  <!DOCTYPE html>
  <!--[if IE 8]> <html lang="en" class="ie8 no-js"> <![endif]-->
  <!--[if IE 9]> <html lang="en" class="ie9 no-js"> <![endif]-->
  <!--[if !IE]><!-->
  <html lang="en" class="no-js">
  <!--<![endif]-->

The points the author made simply aren't good arguments. Yes, frontend development was harder during those days, but not harder in a good or rewarding way.