I think it depends greatly on the cost of supporting the free plans, mine just went a little out of control, I was getting ~100 or more users per day. If it was

I think it depends greatly on the cost of supporting the free plans, mine just went a little out of control, I was getting ~100 or more users per day. If it was really cheap to support them it might be worth the marketing side of things. And of course for VC backed companies this still looks more attractive than not having the free users at all.