> It's actually quite easy to self-quarantine everyone over 70, since they're receiving government assistance anyway (Social Security). But now there are already thousands of job losses from young, healthy, productive people that have almost zero chance of dying from this disease.

Your suggestion is indistinguishable from no quarantine at all (not to mention being incredibly ageist, as there are millions of economically productive 70+ year olds). You forgot the part where even a 'healthy' 25 year-old can spread the disease to others, even if mild or no symptoms appear.