Until something happens near your home (big event, accident, terrorism, etc), mobile cells crap out under the strain of thousands trying to call at the same time, and you're left with no connection.
Maybe! But some folks would like some redundancy on infrastructure, particularly for emergencies. My elderly parents, for example, held on to a land line until they had both cell and fiber internet in their very-rural home. They wanted to have more than one way to reach emergency services (or me) in the event of disaster. I live in a more-urban area and am quite a lot younger, so I'm not as concerned about it.
Most consumer-internet infrastructure is built on the expectation that only a small percentage of people will actually use it at any given time. Chances are a localized emergency will be precisely the time you see the limits of this approach.
Until something happens near your home (big event, accident, terrorism, etc), mobile cells crap out under the strain of thousands trying to call at the same time, and you're left with no connection.
I keep a landline only for that - emergencies.