Dude you can definitely make sand work with good building. People seem to think teams are bad if your not using top vr mons
No one actually said that so quit making assumptions for one thing.
Sand in general is just not a good playstyle in this meta because most team archetypes are heavily against it. Driller has a lot of issues sweeping in a meta with a bunch of shit that can prevent it from sweeping as well as Ash Gren on loads of offensive teams which just revenges you anyway. It CAN work, but you're going to be at an immediate disadvantage in most matchups. No one is telling him he can't use Sand, they are just stating a fact that it is sub optimal in this meta, because it is. Tyranitar is good because it's Tyranitar, so you're better off just using it without trying to make your team centered around Sand.
Yes, you CAN make Sand work, but it loses to a lot of common playstyles in the metagame, so it's not recommended. No amount of good team building can prep you for everything, especially one that's already boned by a majority of the common trends in the metagame. People are just trying to help him because he asked a valid question if Sand it worth building in the meta, and to put it bluntly, it's not lol.
I mean unless you don't really care about winning matches and just want to build Sand for fun, go for it. But like if you're expecting to have a shot at competing with most of the upper ladder, choosing not to use optimal Pokemon is just going to put you at a huge disadvantage. If you want to go balls out and use only C+ ranked mons for the fuck of it, be my guest, but don't be upset when you can't win consistently with them lol.