Why armour gave way to compartmentalisation

What made armour disappear from modern warships?

Missile threats are difficult to armour against comprehensively, making compartmentalisation a more useful survivability investment.

The answer links the decline of heavy armor to the destructive power and varied attack angles of guided missiles. Protecting every likely impact path would add enormous weight without guaranteeing that sensors, weapons, and upperworks survive. Modern ships therefore invest more in subdivision and compartmentalization so damage and flooding remain contained. Armor is not permanently obsolete and could return if a prolonged conventional naval war again rewarded ships able to absorb repeated hits.