I have a brainstorm and want to capture it in a bottle before it dissipates. It's impossible to fit it into a box that allows too few words. A suitably complex thought asks for at least a couple of paragraphs to stretch out its feelers and see if it grabs ahold of anything.
The Twitter input box doesn't give the thought enough room to spark. It too quickly fizzles out, bumping into traffic and weather reports that ground it or pop culture that doesn't pop for it.
When a great weird idea hits, you want it to hit a dry jack pine tree on a hot day and make it smoulder. It might take a day for the jack to catch fire, long after the first flash is gone. Use Twitter to fan the flames, not to light the fire.