It's just decipherable, but very hard to parse, because the subject ('The sweeping social phenomenon Facebook has come to be') only implies the real subject of the verb 'stems from', which is 'the growth and/or the rate of growth'.
As it is, the words 'has come to be stems' invite a meaningless misinterpretation of 'stems' as a noun. When writing, you need to think of the amount of work you are asking your readers to do. In the words of ... (maybe Sheridan):
'We write with ease to show our breeding;
But easy writing's curs'd hard reading.'
Student or Learner