Iframes on the other hand posed a security issue (cross site scripting) - you have two pages living inside the same window, with possible access and trivial attack vectors like creating a page with one iframe being invisible (1x1px for instance).
But that's just an exception, frontend is really a fashion driven developement and there's often no rhyme or reason to why the mob decides to chose one way over another.
At one point people decided that tables are lame.
Iframes on the other hand posed a security issue (cross site scripting) - you have two pages living inside the same window, with possible access and trivial attack vectors like creating a page with one iframe being invisible (1x1px for instance).
But that's just an exception, frontend is really a fashion driven developement and there's often no rhyme or reason to why the mob decides to chose one way over another.