Pitmasters have been NOT wet aging briskets for generations and turned out delicious product. I'm not sold on it.
But lots of the modern pitmasters seem to believe in it. To each his own.
But as with all things, decisions don't exist in a vacuum. They must always be balanced against economics.
Let's say you're Aaron Franklin. I don't know if he ages his briskets or not. But if he does, he has to have fridge space for 3+ weeks of unused brisket sitting there. He has to float the cost of all that brisket 3 extra weeks and carry that inventory. He has to look at the advantage of the aging vs the premium he'll get from customers for the quality of his brisket, and whether it's worth it. If it's a miniscule advantage, he might choose not to do it,
NOT because it doesn't make the product better, but because it doesn't do so to the extent that is economically justifiable.
Now let's say you're a competition pitmaster. The number of briskets you're holding as inventory is much smaller, so all the refrigeration costs are much lower. You're looking not for revenue, but for trophies--and bragging rights. A miniscule advantage may be worth it if it's the difference between finishing 2nd and 5th. If you think it gives you an edge, it's worth it.
For me, I don't know if it makes a difference. But the idea that it *might* improve the product, and the knowledge that it doesn't diminish it, makes me start looking for brisket 3-4 weeks in advance of when I'm planning to use one. Not being in Texas (and BTW I got to go to HEB in San Antonio--and I'm jealous) I might not see a brisket that's the right size/shape/marbling 3-4 weeks in advance. But I start looking because I know that if it sits in the fridge over that time, it'll potentially be even better than if I find one 1 week before. And if I don't see one? It's not enough of a difference-maker IMHO to worry about. I look the next week. The idea of wet-aging brisket gives me the flexibility to start looking for meat before I would have ordinarily done so, because prior to hearing about it I thought that brisket was like most other meat--have to use it or freeze it pretty quickly after you take it home.
Whether you choose to wet age or not depends a lot on who you are, what problem you're solving for, and what constraints you live under.
I don't have a "belief" on whether wet aging is great or not. If everything aligns for me schedule-wise, I'll do it. But it's not a hill I'm going to die on that it's some insane difference-maker.