Telco is a commodity. You want to raise as much money as possible and you want to drive your margins down as it makes competition impossible.
On the web, there are no longer barriers to entry.
If I'm an enterprise, I'll go with Twilio over some 2 week old startup because of its proven track record and the likelihood of being around in a year.
I hate to use this example because its a bit cliche but Google entered late into a field of established players and won. Microsoft beat IBM (this one applies only to the PC, I know IBM is still a force to be reckoned with). Stripe, Balanced, and Square are able to compete with PayPal for accepting payments. I know these arent all enterprise-specific but I didn't take the parent's comment to be about enterprise only.
What you'd do as an enterprise and what real enterprises would do are two different things.