I stopped using #PHP something like 11 years ago. Still are surprised to see how proliferated it still is.
One thing I noticed with most websites I used back then was the overuse of dynamic server features. Most websites were used to be static hosts of content and the bit of flexibility could have been pre-computed.
Oe reason I think PHP became successful was tracking. We were working on some customer API, and they wanted to have the different flows of users in the App tracked. Guess what's perfect for this?
Static websites can't track very well, but when you generate your website with PHP it's just a matter of setting a tracking cookie. Facebook made good use of this.