The 3 bet is a very situational tool. You need your range to be diverse otherwise nobody is going to call you. Let's say you limped in with 10 J suited from middle position, you expect a standard raise to 3x, then somebody 3 bets that again from SB. Are you ever going to call that raise?
Now let's say it's a light 3 bet, you MIGHT call it. Let's say BB is 2$, standard PFR from middle position to 6 and then somebody light 3 bets to 12. Isn't that so much more palpable than a 18$ raise? Yet, it still has the same exact purpose in isolating and keeping out the weaker hands so you have an expectation of your opponent's range on the flop.
I would also experiment with doing light 3 bets in position and maybe even mixing in a few from early with your strong suited connectors so your range remains polarized.
Ultimately, people want to feel that they have a good chance to win and if they know you're only 3betting with your monsters, who's ever going to call?
Experiment also with limping in your monsters vs aggro opponents or people who you know ALWAYS raise on the button or cut off.