This is still true from what I see, but in both families of distributions this is not a big requirement anymore. In my Debian based systems, libx264 is the only thing which requires multiple versions needs to be installed from what I remember.

On the other hand, RPM still doesn't know about reverse dependencies, automatically/manually installed packages, version holds, etc.

Either one is advanced enough to handle a big distribution and have their advantages w.r.t. each other, but I still prefer .deb as a person who works with both. Also, .deb can encode much more information about the software package it contains.