Why reduce font size

Hello,

Do some Web designers prefer fonts too small to read in Firefox with my
preference, Baskerville 14 (Mac OS 10.3.8)? If I needed to call Opera,
Adobe, Microsoft or Netscape, I'd have to be very close to the screen to
read a phone number. Here are a few examples.

http://www.opera.com/company/about/
style sheet
http://www.opera.com/css/screen.css
body is 73%

http://www.adobe.com/aboutadobe/main.html
style sheet
http://www.adobe.com/ssi/css/mainnav.css
some fonts xx-small

http://www.microsoft.com/mscorp/default.mspx
(sorry I gave up)
http://www.microsoft.com/
style sheet
http://www.microsoft.com/h/en-us/r/hp.css
(various, 70% and up)

http://channels.netscape.com/ns/browsers/download.jsp
style sheet
http://cdn-channels.netscape.com/browsers/i/download.css
"is faster....", languages are 11px

http://www.mozilla.org/foundation/
style sheet
http://www.mozilla.org/css/cavendish/content.css
body is small

http://www.apple.com/contact/
style sheet
http://www.apple.com/main/css/global.css
body is 12px

http://www.omnigroup.com/company/
style sheet
http://www.omnigroup.com/resources/global.css
body is 10pt
http://www.omnigroup.com/resources/2004.css
body is 12pt

http://www.w3.org/Consortium/
style sheets
http://www.w3.org/Guide/pubrules-style.css
http://www.w3.org/Consortium/about-style.css
(no size)

The good news is they all have style sheets. :-)

In about 1999, Mac browser vendors changed from 12px to 16px [1,2]. I
assume the problem, if there was one, has been solved. Or do you think
CSS usage is raising shipping and or user preference sizes again?

[1] http://lists.w3.org/Archives/Public/www-style/1998Dec/0030.html
[2] http://lists.w3.org/Archives/Public/www-style/1998Dec/0052.html

Thank you.