Similar token [that isn't quite accurate at all due to the reality of shoes/towels] consider if some family staked out a spoke on a parade route. Left some of their stuff there to 'stake a claim', and then went about the rest of the park. Coming back occasionally to their claim spot to rest or whatnot. Kind of annoying [and most likely, their 'staked claim' would get claimed by security anyway].
Yes it is a bit different when talking about the chairs, since there is the reality of shoes and towels to deal with. Of course, here, my opinion is that if someone can make use of my chair while I'm out on the ski-lift, more power to them, I can move my junk to a different pretty easily. But that's my opinion
More specifically for this thread though, it wasn't so much that they were taking their chairs, it was that they were sitting at their cabana/table. Which is more location issue. I can see some perceptual difference between camping a table/cabana over camping just a seat.
To be honest, I thought that's what the locker rentals were for. I wouldn't personally want my street clothes getting soaked in chlorinated water-park water.