This is an interesting question and a great point.
I can think of a few reasons:
1. Not all of these metrics are readily available in most software systems (incidentally, @Matt Speer is working on some interesting solutions), they have to be calculated manually, and
2. These metrics change constantly. At least daily. Yesterday's numbers are no longer accurate/valid today, and
3. Some of them can be manipulated and/or don't really tell you anything.
For example, you'd think "Days on Market" for rentals could be a crucial metric for landlords/PMs (and a corollary to vacancy), but a PM could take two months getting a property ready to list, and then list it and get it rented in 10 days, reflecting 10 days of vacancy in some customer facing metrics. But isn't it really 70 days of vacancy? (And what if the 60 days of vacancy was planned by the owner as part of a rehab/repositioning and resulted in a planned 50% rent increase - How is that a bad thing?)
Even landlord retention is tricky. It sounds like a great metric to use, but consider: A PM with 10 owners who lost 2 owners because they sold their rentals at the peak of the market has 80% retention, while a PM with 500 owners who got fired by 50 of them for being negligent has 90% retention. Which one is better?
@Matt Speer