You clearly have no idea how dull the LFG tool on classic is.
It’s garbage. And I promise you it won’t be used to the extend you think.
The whole “one stop for all” is just a load of crap.
The amount of trash postings is already high in PTR just so people can spam chat and use BulletinBoard addon to sort through the mess of hundreds of postings in 1/LFG chat.
And now imagine it’s 20,000 people trying to find group.
LFG tool in it’s current iteration is unusable in the way you’re imagining it to be