I stopped myself posting until you gave more information, OP, as my gut assumption was a no. But with more information... it's a big nope from me.
Meeting the odd dog on their daily walk, or even weekly, is more than enough. Yes, some dogs have 'friends' but they also would be fine not seeing them for ages (unless it is a dog they live with). The idea of dogs needing friends is a human concept. Yes, my dogs have 'friends' but these are dogs they have met organically who - being honest - share the same wanky chakras as mine do. They'd be just as happy without having ever met them.
And 'pack' behaviour doesn't exist - anyone touting that sort of nonsense is a fool at best and a cretin at worst. I would be really uncomfortable with anyone who even used it in a business name, or to explain what they do, being in charge of my dogs.
Dog day cares are very different to what you've suggested above. It's only usually 3-4 dogs (usually less) who know each other very well and the introductions are done so carefully. They don't just randomly introduce new dogs into the dynamic. They also often only take the dogs out as 1-2 at a time, not as a big group or a pack.
Ultimately, no one should be in charge with multiple dogs (more than 2-3) - particularly when those dogs might not know each other - who likely have very different needs and behaviours, other than the owner. Managing multiple dogs is challenging enough as it is, let alone trying to do it with dogs you do not know and 'pack walks' sounds like 6+ dogs which is a recipe for disaster - there's a reason good dog walkers only take 2-3 dogs (who they know incredibly well) out at once. Not only do things like 'pack walks' risk dogs being out of control, it also increases the risk of dangerous behaviour (fights, dogs not coming back when called because they are distracted - which obviously then leeches into your dogs behaviour more broadly - bullying, injuries etc).
Would you be comfortable with someone with say 5-6 dogs, that weren't theirs off the lead at the beach when you were walking your dog there? Would you trust that they had total control over those dogs? Would you trust they could stop anything dangerous happening? I would assume the answer to that is no. If so, why would you put your dog in that situation in reverse?