Note the nice relationships around whiptail etc. with again the Suggests a single arrow, but the Conflicts and Provides showing the correct individual relationships.
The versioned conflicts from perl-base are hard to miss...
This graph could be extended even further. The no-skip and show-all options can be used to also show packages that by default are excluded or for which the dependencies are not expanded. However, in a lot of cases this will only reduce the usability of the graph. (Although in the case of debconf the result with -S -VC --show-all is still quite nice.)
It is more likely that you'll want additional packages to be excluded or not expanded because the graph is too big or complex. The contents of a graph can be limited by:
Some packages, especially meta packages like kde, have such a large number of dependencies that it is almost impossible to produce a useful graph.
$ debtree --with-suggests --versioned-conflicts debconf