Poor people and people without decent access to broadband, yes.
For urban folks in the lowest income segments, people who are "highly mobile" (homeless) and so forth, their phone is often their ONLY internet access. (And for email, porn, and a little light web browsing, it's usually sufficient. We're not talking about STEM Ubermensches here.) $40/mo. pay-go cell plans include unlimited data, and are less expensive than most residential internet options. Also, no need to pay disconnect/hookup fees when moving, and no credit checks.
Meanwhile, in rural areas where the population density rounds down to zero, the choice is usually dial-up, satellite, or cell phone service. The POTS systems out there work for analog voice, but are way too old and cranky for DSL. And without the kinds of government mandates that got phones and electricity out to those spots, nobody's investing the money to run last-mile wiring (even though they totally took the government subsidies to do it, but nobody is holding them to it.) 4G is a clear winner in that situation, in terms of speed, latency, and cost.