It really depends on the individual.  It is quite possible to save and invest in a manner where one doesn't have any need to collect CPP or use for a RRSP.  A long term buy and hold portfolio with significant dividend income held in a cash account can produce similar or greater benefits to that of an RRSP.

They don't need to be banned - but like a lot issues related to personal finance people can get themselves into a lot of trouble without taking the time to fully understand what they are doing.     Unfortunately there are far more people making far worse financial decisions who collect employment income and have access to CPP and a RRSP.