Sure, the CSS standard supported CSS tables since the IE6 days, but IE6 didn’t support CSS tables. It wasn’t until IE8 had a decent browser share, around 2011, that it was feasible to use CSS tables. Even here, there were still enough IE6 and IE7 users that I still had stuff like this on my website in 2011:

  <!--[if lt IE 8]>
  <table><tr>
  <td width=640 valign=top>
  <![endif]-->

There was a huge disconnect between what the standards documents supported and what browsers actually supported. There’s a reason they made that “smiley face” Acid2 test in the mid-2000s, because standards support was so bad back then: http://acid2.acidtests.org/ — https://en.wikipedia.org/wiki/Acid2