Yeah, actually, why wouldn't you? No, seriously, what is the actual reason why you would not allow your players to get the items they want? The game already has a 3 attuned items rule. There is literally no reason not to allow your fighters to mix and match their magic items to their hearts content, other than "I'm the Dm and I don't know how to handle powerful parties."
I had a game where I allowed everyone to have basically whatever legendary items they wanted at around lvl 6. Some wound up with more than one. You know what it did? It made them have fun. They felt awesome. One guy critted with a Vorpal sword against the Dracolich on his first shot, and then again when the Dracolich reformed in a new body. Another guy saved the entire group by being the only one who succeeded on his dex save vs that Dracolich's fire breath and therefore the only one who wasn't knocked out, but he used his Staff of the Magi to transport everyone into the Astral realm. Both players still talk about those moments. And yes, I did send a Dracolich up against the party at lvl 6. If they were going to have legendary items, they were going to go up against legendary enemies.
What use is it to hold these things back? "Oh, no, you can't get too powerful, I need to be able to kill you!" You're the freaking DM. You can just say "Rocks fall" and everyone dies. This game isn't about DM vs Players, it's about letting everyone have fun. You know what happens when you don't let players have the items they want? They never get them. They never have those moments. "Oh, but they need to be lvl 17 before getting legendary items!" Bull. Few games ever get to lvl 17, so no one ever uses these items. There are a ton of awesome items just sitting there, all lonely, because all the DM's say they can't play because those DM's don't know how to deal with that kind of power. So I will take them all and give them a good home.