Is RPM on Ubuntu a thing now?

I will start by saying the obvious. In the past, rpm on Ubuntu definitely was NOT a thing. That much is obvious when you search for "rpm" at the top of this page. The closest we'd come was packages like alien that will convert .rpm packages to .deb format.

After a recent experience, I do not believe this to be the case now. In fact, I am sure that it's not.

For context, I will also add that rpm is a package management system a lot like apt/dpkg. However the two aren't interchangeable due to the fact that they each have their own package format used as input. dpkg takes .deb packages, while rpm takes .rpm packages.

While installing a package today with apt install, I noticed a package among the install dependencies named rpm-common. Intrigued, I ran apt search rpm and was surprised by the result. Lo and behold, there is currently a plethora of rpm packages being maintained.

This fact alone is not that surprising. What caught me off guard was the fact that many to most of them were from Ubuntu themselves. As it turns out there is a team among the ranks called the "rpm development team." The packages overseen by them (on Focal) include, but are not limited to:

• rpm -- rpm package manager itself
• rpm-common -- common files
• rpm2cpio -- conversion to CPIO
• rpmlint -- package checker
• rpm-i18n -- localized man-pages for rpm

To further research this, I ran apt info rpm, which revealed that it was ported and originally maintained by the "RPM Packaging Team" at Debian, that it was subsequently passed to Ubuntu and is now maintained by the Ubuntu developers, and that most of the packages above are listed as its dependencies.

So I guess my question is two-fold.

1. When did this happen?

2. More importantly, why did this happen? Is there a change in the works, as with the recent addition of Snaps?

Note: apt info rpm did say the following:

On Debian and derived systems it is recommended to use "alien" to
convert RPM packages into .deb format instead of bypassing the
Debian package management system by installing them directly with rpm.

I just don't understand why an entire app ecosystem is being maintained, but the info warns us not to use it.

Yes, RPM is “a thing” on Ubuntu, but it’s not new, and you’re reading far too much into it.

The reason rpm packages exist in Ubuntu is that they exist in Debian, and Ubuntu automatically imports packages from Debian. In rpm’s case there are a couple of Ubuntu packaging changes applied on top of the Debian packaging, but they are minor (debuginfo handling, and where debugedit is shipped). As a result of this automatic import, the RPM packages have been present in Ubuntu since its very first release: you’ll find the corresponding package entries in the Warty Packages.

There is no RPM packaging team in Ubuntu; it exists only as an automatically-created reflection of the RPM packaging team in Debian.

Furthermore, rpm itself in Debian and Ubuntu is neutralised so that it won’t accidentally be used to install RPMs. It is useful in Debian and Ubuntu to work with RPM archives, and as a helper for alien; not as a distribution package management tool.