Revert "Save work on emitting ignored diagnostics pt 2" (python#20716)

Reverts python#20696

Author: hauntsaninja

mypy/checker.py

@@ -4762,7 +4762,7 @@ def check_simple_assignment(
                 self.msg.deleted_as_rvalue(rvalue_type, context)
             if isinstance(lvalue_type, DeletedType):
                 self.msg.deleted_as_lvalue(lvalue_type, context)
-            elif lvalue_type and not self.can_skip_diagnostics:
+            elif lvalue_type:
                 self.check_subtype(
                     # Preserve original aliases for error messages when possible.
                     rvalue_type,

mypy/checkexpr.py

@@ -2526,8 +2526,6 @@ def check_argument_types(
 
         The check_call docstring describes some of the arguments.
         """
-        if self.chk.can_skip_diagnostics:
-            return
         self.check_var_args_kwargs(arg_types, arg_kinds, context)
 
         check_arg = check_arg or self.check_arg