This is partly because of history. From the 1980s on the mores in cycling was to use skinny tires. Thus there were no road bikes with cantilever brakes anymore. Up and into the 1980s touring bikes were still available with cantilever brakes.

Between 2015 and 2020 we came back on skinny tires and wanted more than 28mm. This was the same time road cycling moved to disc brakes. Most bikes with rim brakes are still using calipers, cantilevers are not coming back. If you want more than 28mm, you will want disc brakes.