By your logic anyone who is retired and has an asset appreciate should immediately sell it, and be forced to move somewhere else.
I cannot afford a home in Portland where I live. I could probably make the mortgage but it’s too risky in my opinion to have a 30 year debt obligation. None of my friends own their own home, not a single one. We’ve all just entered our 40s. The lack of somewhere to live won’t be fixed by a lien, nor will liens on an individuals actual home due at death fix it. It will absolutely incentivize investors who can exploit that, who will pay the liens and add to their portfolio.
If we want more housing at better prices we need to encourage development of more housing. That means making cities more dense and removing NIMBY policies which prevent it. Sure some of these homeowners may be voting for those policies, but they are the minority in larger cities.
The wealth gains far outpace any potential tax increase. They just don't get to keep excess wealth that comes from keeping others out of the area.