Because companies like Walmart exist and use Medicaid as a backstop so they can excuse paying their employees peanuts and not actually providing them health insurance.
65% of the people on Medicaid have jobs.
Walmart and McDonald's are among the top employers of beneficiaries of Medicaid and food stamps, according to a GAO study commissioned by Sen. Bernie Sanders.
www.cnbc.com
So, we can take away Medicaid and a bunch of people can lose the little access to medical care that they have and places like Walmart will need to make a decision to pony up to pay for health insurance which will result in inflation of prices or to employ a bunch of cronically unhealthy people.