Liliana's Contract will need Maskwood Nexus at a minimum, for instance, while Felidar Sovereign demands lifegain, Biovisionary needs clone cards like Helm of the Host, Halo Fountain needs tokens or your opponents to never play a board wipe, and Hellkite Tyrant requires artifacts
Tons of decks have ways to reach into the graveyard, so if you discard the right cards, this cards ability no longer has a drawback
Zurgo can easily produce and kill off tokens with his mobilize keyword, while Neriv wants you to spread things out and make as many tokens as you can for big hand advantage
Yes, escaped creatures have summoning sickness
If they do spend a card getting rid of Indestructibility, though, and another to remove the permanent it enchanted, thats a two-for-one in your favor