Tesla both offers a keyfob for a reasonable price (compared to other car manufacturers in this space, try pricing a BMW or Mercedes keyfob for sticker shock), for people who want one, and a keycard for those who dont want, or cant use their phone.
Using the phone allows people to have "one less thing" they have to carry around, because your average tesla owner in 2021 IS going to have some sort of smartphone. Most people want to carry less stuff, not more, and having the phone be able to be a key means that a family can easily have additional drivers in the home, if they want to, without losing "their" key.
TL ; DR ... if people want a keyfob, they can buy one for a reasonable price, so this doesnt have to be an "either / or" situation.