The first part is looking at where the licenses are applied.
CC BY (and -SA) are mostly applied to creative works: things such as pictures, text, music and video. Whereas the BSD is applied to source code. The issue that you make note of is with attribution.
So how do we attribute with both licenses?
With the Creative Commons license we simply need to provide credit. Most creative works which are licensed under this license also don't have a large string of notable contributors: it's generally a sole person that makes the work. Because these projects didn't normally have more than 3 contributors, it's never been an issue.
Any open source project will likely have many different contributors who will contribute in many different ways. Such a list is would be long. The issue with the BSD wasn't always in attribution, but when promoting anything that made use of the project. Look at this clause:
- All advertising materials mentioning features or use of this software
must display the following acknowledgement:
This product includes software developed by the
Hmmm... This isn't just providing attribution in the window of the program, but this includes any advertisement, or promotion of the new program. That would've been problematic: loss of space on the print. The biggest reason was that such notice wasn't even necessary: All that was needed was that the original developers got notable credit in their work.
This was the 4-clause BSD license. Newer versions of the license don't have this clause, and are commonly used in multiple projects.