I feel like you’re viewing the play dates from a very human perspective rather than a guinea pig perspective. The advice you’ve read saying that play dates are bad is written with the social and welfare needs of a guinea pig in mind, and like I said those differ greatly from humans.
Guinea pigs live in a strict hierarchy, that’s the only way they are happily friends with another guinea pig. When guinea pigs don’t have a hierarchy determined, this is quite stressful as each guinea pig has to ‘fight’ for their place. Even if you can’t see dominance, they are still dealing with quite a stressful situation in trying to determine where they stand, if they need to be on guard, becoming familiar with the other piggy, etc.
But also, if they do get along well, it’s very cruel to take that friend away from them. I recently had to separate two of mine after they’d been together about a month due to quite a bad bullying situation. From this separation, the pig that was doing the bullying essentially went into acute pining. Acute pining is what happens when a piggy loses their friend to death, they stop eating, they sort of just give up on life. Even though the bond between my two wasn’t the most functional, the social needs of a guinea pig is so great that one of them just didn’t see the point in living really.
Every time the two piggies will meet, they will go back to square one. Guinea pigs don’t view play dates as play dates, when two guinea pigs interact they’re trying to work out if they can be together forever. To have that process stopped and started over and over is stressful and also cruel. Whilst we shouldn’t view this in human terms, it is kind of like meeting someone and saying “hi, how are you? The weathers terrible, isn’t it? Oh, you got rained on? Well, okay bye!” Just on a constant loop, you never get further than that point any time you meet them. They aren’t your friend, in fact you barely even know them and it’s probably a bit uncomfortable. Especially if the conversation never goes beyond that point every time you meet. That’s kind of what happens between two guinea pigs that are given play dates except with a lot more stress. Like I said, they live in a hierarchy and every time they meet they have to be ready to determine that hierarchy.
If both you and your friend are able to each get a permanent friend for each of your single piggies, then you should. I’m not sure why you’d go against advice you’ve read to give each of your piggies play dates together when you both seem in a position to find suitable friends for each boy. The reason play dates are advised against is because they don’t cater to the actual needs or feelings of the guinea pigs involved, they only seem like a good idea to humans because the way we socialise is vastly different to guinea pigs