As a former Radio Telephone examiner, I can tell you that is not true.unfortunately I cannot solo without it.
You can turn on the radio and listen without a certificate.
You only need the certificate to transmit.
And, it is NOT a CARs violation if you do. TC doesn't care.
Lots of American pilots come to Canada and transmit without one,
and no one cares.
Back to reality ... I am glad that you had the chance to fly with a really
experienced instructor. Not all the time, but sometimes, a really experienced
instructor can help.
Actually, just flying with any different instructor is really good for you.
Students hate flying with different instructors - worse on different types
of airplanes - but that's how you get good.
If you flew with 100 different instructors on 100 different types, you would
be a very knowledgeable pilot, indeed. That's called Test Pilot School.