Gaming HTML5 took out frames.

[Rydian]

The following elements are not in HTML5 because their usage affected usability and accessibility for the end user in a negative way:

frame
frameset
noframes

http://www.w3.org/TR/html5-diff/

 

[omgdaniel]

Well, frames aren't really that great looking anymore. And most browsers would be backwards compatible with

 

[Costello]

frames kinda suck, iframes are better

 

[Originality]

Frames used to be a good mechanism to reduce loading times for ye-olde-modem connections, as well as helping organize sites slightly better. Admittedly, iframes do the latter much better, but still...

Then again, theoretically everybody is supposed to be on broadband now. Even mobile internet is supposed to be faster than 56k dialup (even if only marginally more reliable).