When you purchase a program on a CD, what you typically own is a physical copy of the software and a license to use the software. This license outlines what you can and cannot do with the software. Common rights granted include the ability to install and use the software on a computer, and possibly to make a backup copy for personal use. However, you do not own the software itself in the sense that you could redistribute copies, modify it, or use it in ways not permitted by the license.
This legal concept of software ownership has not fundamentally changed in the last 20 years, but the specifics of licensing agreements and the enforcement of digital rights management (DRM) have evolved. Two decades ago, software often came with "shrink-wrap" licenses, where the act of opening the software's packaging constituted agreement to the software license. Today, software licenses are more commonly agreed to digitally via click-through agreements during the installation process.
The shift towards digital distribution and cloud-based services has also introduced new licensing models, such as subscriptions, which grant access to software for a limited time, further emphasizing the distinction between owning a physical copy and owning the software itself.
In summary, owning a program on a CD grants you a license to use the software under specific conditions, not ownership of the software code or the right to do anything you want with it. This principle has remained consistent, though the details of how software is licensed, accessed, and used have evolved with technology and distribution methods.
tl;dr: don't believe strangers on the internet about digital rights, including me
With that said, you're splitting hairs for no good reason imo. When people talk about having owned software they mean it in the way people talk about owning copies of books or movies or music, which is to say they don't mean "ownership of the software code or the right to do anything you want with it." Basically nobody buys a copy of a book or the like thinking they somehow have the full rights to them nor that they could do with them what they will, outside of maybe sharing them with a friend or selling them when they're done with them.
Really, the law simply hasn't caught up sufficiently with digital media to properly address software ownership in ways that meet the interests of both businesses and civilians. That said, the simple fact that you can sell a used copy of software on physical media is sufficient to indicate that your point is rather weak. The absence of a digital infrastructure to enable a similar sort of secondhand market is more of an indication of the failings of existing legal systems to have kept pace more than anything imo. There really is no good reason that one couldn't exchange or sell used (licenses of) digital goods beyond businesses interested in maintaining control over digital markets, governments failing to check them, and civilians failing to compel their governments to check them.