I think it is a good idea to own everything if you dive more than a few times a year locally (where you drive (or walk?) and can bring your own stuff from home.
For those who don’t dive locally, I would say still own everything, except tanks and weights which you will not want to haul on a plane. Rent these heavy items near your dive site and maybe additional thermal protection if the water will be colder than your owned wetsuit is designed to handle.
If you do dive locally, but not very often, again I could see renting tanks so you don’t have those maintenance costs for the months (years) between dives when you don’t use them. I still think owning everything else is worth it to have that familiarity and historic knowledge of your regs, suit, BC, etc.