I amplify Kona's response as I'm the one who had to do the custom integration, but it didn't stop with Canvas and Jenzabar, it extends to Jenzabar and anything (single sign on, student accounts, student email, public website, ...).
I also see it from the faculty perspective and I had a little training 15 years ago on web accessibility and it drives me nuts. I often log into the server and access the database directly because finding it through the web interface would me take longer. I've also written a lot of custom interfaces to speed up the queries that people use (like pulling all of the relevant student information onto a single screen).
There isn't a single field primary key for a section - it's a combination of session, year (there is no "term" field), course number, and section number. Everything I do has to be keyed off those four values instead of just referring to section 12345. I much prefer the Canvas way of doing it with having an integer ID for everything (except for page view log data).
I will say, though, that we're on an older version that we're trying to move off of -- or that the company doesn't want to support any more -- and so I can't speak to the new interface. I've been warned that all of my custom integrations will break when we do that. We may take the opportunity to re-evaluate systems at that point, but we have about 28 years of data in this system so I don't hold out hope that we will change.