Because your index.php did not need to dehydrate and hydrate.

Back in the days the apps were unresponsive, clumsy and user unfriendly.

You really can't compare web apps with old websites or even forum software like phpbb.

EDIT: The down vote of the PHP developer which still wants to write phpBB forum websites :)

Good luck with that. I'm waiting for the article that complains about frontend development ;)