I actually just bought a McLane power reel mower a couple of weeks ago. There are applications in which they are beneficial aside from cutting short.
While I live in the north I have a highly shaded lawn. The vacuum from a standard rotary mower destroys fine grass. My lawn is far too huge for pushing by hand. Additionally it works great on other southern grasses.
The varient which I bought is a 5.50 gross torque model (probably 4hp equiv), 7 blade reel. It just flies through thick grass with ease, the reel spinning at insane speed, but guess what no dust, exactly what I'm looking for as I want the fine grasses to establish.
I have two older power reel jobs, a Craftsman using a 4hp Tecumseh, it kind of rolls over the grass like a push varient discharging out the back. It currently doesn't run, is a pain to maintain and is nowhere near as smooth as the current sutff.
If you have some fine/short growing grass or perhaps zoiysha/bermuda, the results are amazing, I can make my back yard look super smooth.
They made them for a reason in the 60s and there are reasons they still exist today but, you're going to pay out the nose for a current one (I got mine on clearnance for 70% off and it was still $300), but there is a reason people use them.
They also chop grass at a different angle, smootly, good for mulch, less hamrful to the existing grass.