Why do you say everyone needs a single stage?
If I have my LNL-AP set up for a production run of 1000 or 1200, my usual run of say 9mm, and I have a hankering for try some new bullets or new powder in my 357mag, I will do my ladder loadups on the Single Stage to find what works the best instead of changing my setup on the LNL-AP.
I pull all the bullets I need to pull on my single stage, it's just so much easier than a kinetic hammer, (but you will still need the kinectic hammer for round nose 9mm).
I do a lot of my priming on top of my single stage, for my less common calibers I load for. Especially if I don't have a shell plate for the LNL-AP.
I guess I'm saying a single stage press compliments a progressive press in so many ways it's hard to list them. I know once I get my LNL-AP tune in perfect for a specific caliber I really don't want to change my setup on the AP for a run of 25 experimental loads.
I have two progressive presses now, one is a LNL-AP w/case feeder, the other one will be replaced this year with a second LNL-AP with no feeder. Even with the two APs the Rock Chucker single stage will still have lots of work. They are just so easy and so versatile (but very slow) that I don't know how you can be without one.
The Lee classic turret press is a self indexing turret press and parts like turret plates are cheap and work well. There are $13.00 and you populate them with dies and just swap out the whole turret for a caliber change. You can take out the indexing rod in about 10 seconds and have a single stage press or leave it in and have a self indexing turret press that is probably one of the most versatile and most flexible presses on the market. It would be your single stage to compliment your AP.
If you start out with the LCT press instead of the hand press, you won't have a really slow press like I have. But you do need something better than a hand press to start with and like I said in my first post, hand presses are cheap, you can buy one any time.