I have heard that comment many times and yes its not a bad idea. However there are often 2 key problems.
Firstly like the one in the picture many are never cleaned or checked so are almost impossible to see through.
Secondly so many are in poor positions they make any field of view severely restricted.
As a principle its a good idea but like so many things in practice over time that becomes corrupted.
Make sure you check your simple basic security features before you need them.