I don't know where this is all going, perhaps there are too many of us telling each other how much we all know.
I would like to go back to "why does the average PPL in a light aircraft need to side slip"
I was taught sideslipping as a 17 year old SPPL in various aircraft as a way of loosing height in the least forward distance.
I still use side slipping for the same reason today (30 years later)
Example: PA28 (any model)
You are down wind at a height of 1000 ft, you expect to turn base and fly a 2 1/2 mile final, decending at about 500 fpm at 70 knots,
ATC request you "to keep it tight" and you turn on final at just under 1 mile, but are still at 800 feet, even with with full flap you are not sinking fast enough. If you put the nose down you will speed up and never get in.
This is where it is useful to side slip, to loose the excess height and still land at or near the start of the runway.
Done properly at the correct speed (ie.normal approach speed or slightly less) you will not damage the a/c nor will you spin or loose control in any other way.
Tony R