It also has to do with the ad networks. For example with Google adsense, they really encourage you to use responsive ads:
"You can use responsive ads to provide a great user experience on your pages. They look good on desktop, tablet, and mobile devices. "
But when you use a responsive ad, google can dynamically decide the height of the ad. They don't want you use use a fixed height container:
"The parent container has fixed or limited height. Responsive ads should not be placed inside containers with a fixed or limited height, as they may be taller on some devices or browsers. If you need to limit the height of your responsive ads, you’ll need to modify your code and use CSS media queries to set the height of the parent container."
Which is strange since Google will also penalize your site for shifting all the content after the initial paint. So they won't let you define a maximum width or height, but will also penalize you for having dynamic width and height elements.
"You can use responsive ads to provide a great user experience on your pages. They look good on desktop, tablet, and mobile devices. "
But when you use a responsive ad, google can dynamically decide the height of the ad. They don't want you use use a fixed height container:
"The parent container has fixed or limited height. Responsive ads should not be placed inside containers with a fixed or limited height, as they may be taller on some devices or browsers. If you need to limit the height of your responsive ads, you’ll need to modify your code and use CSS media queries to set the height of the parent container."
https://support.google.com/adsense/answer/9183362?hl=en&ref_...
https://support.google.com/adsense/answer/9183362?visit_id=6...