This suggestion eliminates bugs that are introduced by unsafe typing, sure. But race conditions, logic flaws, misconfigured tools and almost every class of web vulnerability wouldn't be eliminated just by implementing this.
Most vulnerabilities do not derive from a single faulty tool or framework, but the incorrect combination of several (faulty or not!) tools over a sufficiently large attack surface.
Most vulnerabilities do not derive from a single faulty tool or framework, but the incorrect combination of several (faulty or not!) tools over a sufficiently large attack surface.