Why have InDesign default web resolutions not changed since seemingly 2008?

These are pixel sizes which only match actual pixel dimensions at 72ppi, as far as I understand. InDesign isn’t a pixel-based app so anything you intend to do in pixels may not necessarily match the dimensions you specified in InDesign on actual monitors. 

Why have InDesign default web resolutions not 

Hi ​@Serendipitous_Eagle0100 , If you don’t like the application default for new documents, you can change yours by closing all documents and choosing File > Document Presets > Define > [Default] > Edit. All of the application preferences defaults can be changed to your preferred defaults with no documents open

Hello ​@Serendipitous_Eagle0100 

Thanks for reaching out. I understand that this functionality is important to you. Would you mind creating a UserVoice for this feature request (https://indesign.uservoice.com/) and adding your comments there? Doing this will help us prioritize this request, and you will be notified of any updates.
 
Feel free to reach out if you have more questions or need assistance. We'd be happy to help.
Anubhav