You are not wrong, if you raise $60M then you have set certain constraints on your future. That said, as a primarily bootstrapped company with good traction and a reasonably world wide 'touch' if they aren't operationally cash flow positive yet I would be surprised. They have hit an interesting sweet spot between transactions (always a useful volume business) and an aged infrastructure (SMS). It was a space I would have expected Twilo might compete in.

So in this case it could simply be the cash they need to either prep for an IPO or to solidify their lead so that if they are taken out it is expensive (and thus a good return to the Series A investors).