These companies maintain that even though you possess a PDF, you still do not own it and do not have the rights associated with ownership.

I would consider it more problematic if the author of the paper got any of that and not the journal the author had to pay to be published

When you rent something, you can share it. You rent a car, you can have passengers. You rent an apartment, you can have visitors. You rent a tool, you can lend it to your neighbour.

Then it's rent and not bought. That shitty excuse "akshualy you only bought the license, can't do what you want with it" is just abuse, because the buyer never gets clearly informed beforehand.