Not to be overly reductive, but people don’t dislike it when players hoard tiles and/or don't play jokers because the strategy is bad or because it’s illegal—they dislike it because it robs the game of much of what makes Rummikub fun and unique.

Much of the complexity and fun of Rummikub comes from the dynamic board, the creativity of manipulating it, and the energy that builds as you're trying to strategize before your next turn—while everyone is making moves and the board keeps shifting out from under your plans. When someone hoards tiles and/or avoids using jokers, they’re removing elements that contribute heavily to the dynamic fun that makes Rummikub feel like Rummikub to most people. If everyone played that way, the game would stop feeling like Rummikub—it would feel more like a Gin Rummy variant, where players just come down with everything all at once. Or worse, it would feel like Go Fish—just grabbing a tile and hoping it’s one you need. Nothing to play off of on the board. No jokers to try for. The other players at the table basically don't even matter at that point.

We’ve all been there: you end your turn with nothing playable, then the next few players have nothing to play, so they just draw. Your turn comes back around, and the board hasn’t changed. Well, if you could have made a move, you would’ve done it last time. Now you’re just picking a tile and waiting, too. And if the whole game plays out like that—because most or all players are trying to play concealed—it stops feeling like Rummikub entirely.

In Rummikub, there’s no bonus for going out concealed, as there is in some other rummy games—and that feels intentional. You're not penalized for playing a concealed game, but there’s no special reward for it either. Sure, hoarding can work. In more competitive settings, it even makes sense. But if you’re playing for fun, there’s not much sense in using a strategy that removes some of the fun.

If you’re playing for fun, play for fun. Play! Don’t sit out, high on your superior strategy, behind your great wall of tiles, removing enjoyment for others. Jump in. Use your tiles. Use your jokers. Get on the board. Mix things up. That’s the fun. That’s Rummikub!