I hear this more frequently nowadays, but it really is kind of misplacing the blame for this change. Steam went for this model precisely because many of the bigger game companies to this day refuse to sell their games as anything but a heavily restricted license. And Steam as a storefront does have to cater to them in that regard, especially back then. Even physical disks as others pointed out were technically not something you owned, but rather that resale and such was not enforced or enforceable. (You would definitely get some stern letters if you started copying and selling those games at larger scale, even if you 'owned' the original copy).

People do still sell DRM free games on Steam that you can copy and distribute to essentially your hearts extent without Steam ever getting involved. The license you have is for Steam to provide you the download service so you can get your digital copy (and a bit more). If you care about people owning games, then it's up to you to support and buy from the kinds of companies that don't provide you a license or (more likely) where the license is unrestricted enough to fit your description of ownership. The middleman like Steam you buy it from shouldn't matter if they don't exert undue control beyond that. And at least being on PC if you really must buy something with DRM you have options to remove it.