Yes it is the same as you say when every kid grows up. But for me - it doesn't matter if 3x3 was the same with me vs the kid that plays 3x3 is now. - For example, as a guard which I was- 3x3 was much easier for me. I can get off my shot much easier. I could drive with less people to impair my drive to the basket and take a shot or make a pass with less interference. And overall it was easier for me to make an offensive pass. More players out of your field of vision can read your pass. You can make soft passes on 3x3 that you can't get away with as much as a 5x5.
As a defender - I was good one-on-one for someone my size- but if I couldn't match up well- it was always easier to limit the offensive player on a 5 on 5.
3x3 imo is more 1x1. It just that makes it much different. It doesn't mean It doesn't make me think that it's all bad. But whatever. Just my personal view.
A solid pick and roll game in 3x3 is very effective, as Stef demonstrated time and again. There's not other players coming to play weakside as often as in 5x5. She hit her layups, jump hooks etc. And when help did come, she could still hit them.
Plum and Gray could break down defenders on drives from outside, per your 1x1 observation.
The game is fast. As an older player, I find I can get by as a power forward, setting screens, rebounding and hitting an elbow jumper. The back and forth here in 3x3 would wear me out!