The problem is, if you stick with just the top 10 hands in a tournament, you are just going to blind away, as you're not going to get those hands often enough of the time to chip up enough to stay viable in a tournament (save for the extremely few rare exceptions). Because not only, by playing this way, would you have to get said top 10 hands often enough, but you would also have to ensure that you get paid off with these hands nearly every single time, which is nearly a statistical impossibility.
In smaller stakes tournaments, there is merit to playing a bit tighter as you will get paid off a higher % of the time, granted, but still not high enough to reduce your hand playing to the top 10 alone. Furthermore, there are just some situations you have to exploit, where your hand strength really doesn't matter. On the bubbles, for example, when ESPECIALLY in a low stakes tournament, a large % of players will be folding to get to the money, there's a lot of chips you can pick up without ever getting to showdown, making your hand strength irrelevant. Or sometimes, by paying attention to how your opponents are playing, you can spot a weakness and repop them in various situations to steal chips.