Patronage, think of it like a mentor.
If you got toe cancer tomorrow, there is likely a cancer support group. It does not mean that your friends and family cannot support you through this treatment. People who have BTDT are also important in getting through.
Same goes for prayer, while we ask everyone to pray for us, sometimes it helps to ask a Saint to pray for us, one who went through or knew about the same thing when they were on the earth.