Think you are missing the point as to why PRTDs based on H&C are awarded. It is for permanent moves back to Canada. It is not meant for people to obtain PR cards with the knowledge they will not be able to meet their RO. For example if you have a sick relative and will continue to need to spend a large portion of your time abroad then applying for PRTD based on H&C may not make sense and applying later when the health of the relative has been resolved may be a better option. There are examples when multiple entry PRTDs are awarded or can be requested that make sense. For example if you are living abroad with your Canadian partner and want to visit Canada and have no intention of moving back to Canada in the near future then a multiple entry PRTDs is sometimes awarded or can be requested.