The problem is that Twilio is not profitable. They wouldn't need to show a hockey stick if they were. Investor-subsidized, non-profitable companies have to sell growth to their investors because they have no other fundamental to point to.
Indeed, either take the investment and the dragons that will come to burn your village or grow slow and own your future (Basecamp/37signals), but make peace with that you’re always going to be small (but it’ll at least be yours).
instead of posting a poorly informed take, you should go and have a look at their list of product offerings. They havent been just a "notification API" for a long time now.