Why do Illustrator and Balsamiq have different font size defaults? Is there a standard for web design?

I just started using Balsamiq for mockups and I noticed they only have a limited set of font sizes (presumably to guide the user to follow design best practices). I then wanted to make a more detailed mockup, so then I started on a second iteration of the mockup in Illustrator. I noticed there's a different set of default font sizes in Illustrator.

For the purposes of web design, is there a standard set of font sizes? I'm wondering if there are best practices I should follow.