You want an example of how it can be done, eh? Alright.
Retail has already provided an example of how it can be done.
In the end it comes down to what’s called reward schemes and the intended perceived worth. An easy example of creating that sense of worth in a player when you design a game, is to make it very exclusive. As in that it excludes a lot of people.
This exclusive effect can be accomplished either via difficult requirements, and the more difficult you make something in a game then the fewer people will end up accomplishing it, or you can do it via a very low chance RNG rarity.
For example, to compete in the m+ dungeon invitational on stage, you need to beat some of the best WoW PvE teams in the world. This, by default, excludes everyone who can’t measure up or can’t make the trips to the LAN events (including the big stage).
An example of rarity deciding how many people gets excluded is the Big Love Rocket. iirc it was only like, 1 person in the whole world who got it the first year. This really drove up the sense of worth of that mount for a lot of people during that time. Nowadays it’s not so rare due to not needing to be max lvl anymore, and lvling itself was made easier a long time ago, so it really pushed down its perceived worth for many.
An example of the opposite of these two is being given something for nothing. Like the hearthsteed mount promotional event when hearthstone first came out. You just had to complete a very simple task in hearthstone and then you got the mount in WoW. There’s not a lot of people finding any value in this, except for maybe some of the ones who missed it when it was a thing. If it would still be a thing, then even fewer people would find value in it.
Ok, so with those examples out of the way, as the expansions progressed and BG reputations losing their worth with fewer rewards, and items still being for lvl 60, it made less people interested in them since they had also turned off the rank system. Kind of like how many PvEers do BGs these days in Classic, because there are many rewards with a high perceived worth for doing them.
So what they did was first to introduce miscellaneous achievements with the new achievement system, and then also Rated Battlegrounds. This, hooked into the arena reward scheme, but also with its own titles and eventually its own transmogs of the old GM/HWL stuff once transmogs became a thing, it created a new sense of worth in doing those.
But the unrated battlegrounds still existed as well. However, what occurred was that many players who focused on rated content due to its higher difficulty and more exclusive rewards, stopped doing unrated BGs. Unrated BGs became a thing many people did to 1. kill time, and 2. get the miscellaneous achievements. This hasn’t changed to this day. (There was also a time when you could cap conquest/honor in unrated BGs, but that was later changed.)
So what this created was a very different gameplay experience depending on what you were queuing for.
Then you got the premade exploits becoming prevalent by certain regions, and the consequences of these can still be seen in the world rankings of amount of HKs on a single character.
So what can you take from all of this?
It means 1. people will do whatever they can to do premade exploits again, should Blizzard put in any arbitrary limitation to the premades which makes such a limitation ineffective in the end, and 2. it changes the reward scheme.
They’d basically either have to increase the rewards dramatically for the “premade only” queue, thus making it even easier for people to get those rewards which drives down the perceived value of them (as well as impacting PvE more than it already has with even more people getting those upgraded gear rewards from reputation), and also drives down the interest in doing BGs by the many PvEers who feels “stuck” in the BGs as they are now. Since they’d finish faster with their reasons for doing them, after all.
Or they can remove the rewards entirely from the “solo only” queue, which keeps that perceived value people see in the reputation rewards and/or rank rewards, while also keeping the interest in the “premade only” queue relatively high. It also serves to reduce the motivation to perform those premade exploits.
Bottom line is, they can’t reward the same things for two very different ways of progressing.
Which is why the thought that PvP should be possible for solo players with all its “rewards and riches” and so on in the same speed as the ones who tries harder to get 'em, is nonsensical. To start with, if fun is all they care about then rewards shouldn’t matter to them.
This is also why the simpler solution is to just remove the root of their frustration, which is that premades can get matched against randomly matchmade teams. Except not in the way they want it to be solved, which is to make solo queuing the easier option, but rather to just disable anything less than full premades from queuing.
If only full premades can queue, it brings both social benefits, as well as gets rid of the reason why they’re frustrated, which is the perceived inferiority of being a randomly matchmade team vs. a premade.