Linking the launch of the Threads to Instagram gave users a shortcut to the hardest part of going social: building a network. Slate called this a killer feature that might bury Twitter. Reportedly hitting 4 million users within hours and 30 million within 24 hours, the app was heralded by many outlets as The Fastest Growing App Ever. But, will people keep using it? And, will there be room for marketers on the platform?