As a vintage-bike rider, and having now worked as the parts guy in a dealership for 9+ months now, I understand both sides of this pickle.
I routinely take mild verbal abuse from people who can't fathom that a dealer has to special-order the sprockets/levers/clutch plates for their bike that's been out of production for 15 years. And I get it. But carrying all this stuff as a multiline dealership would mean becoming a ginormous museum of parts with dozens of million $ in mostly-dead inventory.
Your specific bike is made up of thousands of parts, and there have likely been multiple revisions of it. Every variation of a bike is sold in relatively small numbers in a market like Canada.
One example - I special-ordered a fuel tank for a 2020 M109R the other day, in white/black with copper stickers. The odds I'll get another call for the same part # by the time I retire in ~25 years are effectively zero.
Honda's Toronto warehouse looks to be about 100,000 square feet based on Google Street View. That's one of three major warehouses in Canada.
Parts take up a massive amount of space and money. We can get them in fairly quickly in most cases, unless your idea of "fairly quickly" means same day. I doubt there ever existed a world in which you could walk into a motorcycle dealership and instantly walk out with whatever bit broke on your bike, beyond near-universal-fit consumables like chains. Even brake pads are tricky - EBC's catalogue is a 645-page brick.