Just to update, this is no longer true. If you show up, you will be asked if you have an appointment and if the answer is no, you will be turned away. I didn't even get inside the building.
Further, if you want to make an appointment, expect to be grilled as to the reason you have to travel, and provide proof you've booked the travel. Except they recommend you don't book until you have the new passport. Which you can't get without booking. I'm between enraged and furious with this nonsense.
See:
https://www.canada.ca/en/immigratio...n-passports/new-adult-passport/apply-how.html
If you’re applying in person
By appointment
You must provide
proof that you need the passport. New