The collectible yoyos you’re referring to are usually yoyos that simply stand the test of time… the reality is that most yoyos fall by the wayside and get kinda forgotten over time, but there are always a few models that have staying power for one reason or another. To answer your question about RSO, they’re simply just too young of a company still - anything they release is still too new to be considered Peak level collectible. Plus, many of their designs are modern interpretations of the ultra-collectible yoyos you’re referring to - it’s unlikely that they’ll ever be more popular or collectible than the yoyo they’re based on.
Although it’s impossible to say what yoyos releasing now are going to be collectible, I find that one of three things makes a yoyo collectible in the way you’re talking about. (1) Historical significance in terms of pushing yoyo design forward, (2) The yoyo isn’t being made anymore/the company isn’t around anymore, (3) Has a unique aspect that sets it apart from other yoyos (aesthetically, design wise, etc). If you have just one of these, it’s probably moderately collectible. All 3? That’s a recipe for a yoyo purchase that puts a major dent in your wallet. The OG Peak for example has all three of these characteristics.
But really… you never know what’s gonna be collectible down the road. Anti-Yo is obviously one of the most highly collectible brands out there, and anything from them is gonna run you several hundred bucks. But there was a time when the Bapezilla 2, a yoyo that is now highly coveted and regularly sells for several hundred dollars, infamously sat unsold in stores for years. Yoyos and yoyoers are weird like that.
Most yoyos are too new. It usually takes 10ish years at least, give it time. And we have more yoyos than ever now, the market is so so so saturated - pretty much anyone can make a yoyo now. If you can afford one RSO, you can afford to pay a designer and run your own yoyo lol. But there were less companies back then, and there were more innovations back then. I feel like it’s quite a bit more difficult now to make something that hasn’t been done before - it’s possible, and people do it, it’s just getting rarer and rarer.