First, let me state some of the philosophy behind RPM. One design goal was to allow the use of "pristine" sources. With RPP (our former packaging system of which none of RPM is derived), our source packages were the "hacked" sources that we built from.
Theoretically, one could install a source RPP and then make it with no problems. But the sources were not the original ones, and there was no reference as to what changes we had to make to get it to build. One had to download the pristine sources separately. With RPM, you have the pristine sources along with patches that we used to compile from. We see this as a big advantage. Why? Several reasons. For one, if a new version of a program comes out, you don't necessarily have to start from scratch to get it to compile under RHL. You can look at the patch to see what you might need to do. All the compile-in defaults are easily visible this way.
RPM is also designed to have powerful querying options. You can do searches through your entire database for packages or just certain files. You can also easily find out what package a file belongs to and where it came from. The RPM files themselves are compressed archives, but you can query individual packages easily and quickly because of a custom binary header added to the package with everything you could possibly need to know contained in uncompressed form. This allows for fast querying.
Another powerful feature is the ability to verify packages. If you are worried that you deleted an important file for some package, just verify it. You will be notified of any anomalies. At that point, you can reinstall the package if necessary. Any config files that you had are preserved as well.
We would like to thank the folks from the BOGUS distribution for many of their ideas and concepts that are included in RPM. While RPM was completely written by Red Hat, Inc., its operation is based on code written by BOGUS (PM and PMS).