Generally, the way tribal decks work (with a few exceptions I'll mention later) is that they want to play a lot of creatures and then cards that make those creatures' types matter
It forces a sacrifice across different permanent types , depending on mode, which means it can hit creatures, artifacts, or enchantments without targeting
Most Magic cards have mana values somewhere between 1-6, so the chances of you having a blue card with the correct mana cost (or enough lands available to pay for it) arent all that low
Theres flavor, good theming, utility, and power, with nothing being too close to generic good stuff
And it can even do it repeatedly where Entomb typically cannot