muy imbècil

recently i heard a very wise phrase from an argentinian:
“Un imbécil te puede decir algo constructivo
Que tú lo puedes aplicar para tu vida
Esa persona no va a dejar de ser un imbécil”
which translates as:
“Even an imbecile can say something constructive and applicable to life, but that doesn’t stop them from being an imbecile”
How do you interpret this phrase?
For me, it means that it is important to develop critical thinking:to evaluate not people, but the content of their words.