I have mixed feelings on this topic. I own several different 3rd party lenses in the EF mount that I routinely use on my R and soon my R7 when it arrives via the adapter. I only own one RF 3rd party lens and it's a manual focus, the Lensbaby 56mm Velvet. As I understand it Canon is only limiting RF mount auto focus lenses from 3rd parties. And for the few who own one of the first RF auto focus 3rd party lenses they can still use them as long as Canon doesn't change something in a future firmware update. I think many of the 3rd party lens companies have come out with some really nice lenses for Canon EF as well as Nikon and Sony, often smaller and faster than a what the main companies alternatives have if one exists.
That being said I shot commercially for 35 years and in all those years I had to go after several users of my images that I had copyright to. I sued a high profile politician's re-election campaign for illegal use of an image of his opponent I had been paid to take and ended up being awarded $20,000 in Federal court. So from that aspect I see Canon's reasoning. The R cameras and RF mounts are very different in design and no doubt a lot of research, development and money went into making them. Now other manufactures can easily back design a lens to work but in the end their efforts might end up being negated in court.
Tony Northrup (OK, I know not everyone likes him) did a video on this subject this past week. He makes some good points and says in the end Canon may be hurting themselves as well as hurting a lot of photographers. Time will tell.