This isn't about accepting or denying coverage based on a pre-existing condition. Its about rationing care.
The cost of care is the problem that all countries with universal/govt provided care are facing. They have limited choices regarding costs: increase taxes and fees to increase the availability of care; keep costs (taxes and fees) low and ration care; reduce the payments to health care providers to increase availability of care. None of these solve the problem and lead to additional problems.
All of the countries that I have looked at (Canada, England, Taiwan, Japan, Germany) spend less than the US as a portion of GDP, but they are all facing serious financial troubles. Some are about to collapse (Japan, for example, where 50% of hospitals and clinics are in the red) because reimbursements don't cover actual costs. SOme are facing shortages of health care workers and reduced quality of care (Germany, for example, where doctors went on strike). Some are facing significant wait times (such as Canada, see the CIHI report cited earlier).
"You're sick and will probably die in a year, so we're not going to sell insurance to you." Sounds like rationing to me.