It's easy to confuse access to knowledge or having knowledge as someone being dumb or otherwise. I have to agree with the OP - many techonological things have reduced the cognitive and intellectual abilities for the brain to work. Like any muscle, the brain needs to be worked. That's ONE of the reasons why so many elderly people get the onset of dementia after retiring.
Many people in society now are innumerate, illiterate and are rapidly becoming incapable of simple or independent decisions without being led. Studies have shown that commercial tv programmes have the language of a 12 year old. And that's why intelligent people get bored with TV as a form of entertainment - and the reverse happens too - commercial TV then dulls or dumbs down people.
I know one family, when the internet first become a huge phenomena about 15 years ago here, who bought their teenager a PC for Christmas. They hardly saw her after that - she was always in her room chatting or mindlessly surfing the net. So many adults and teenagers now are incapable of social intercourse due to online gaming. They become adrenaline addicts, break into shops for online games and are devoid of showing genuine emotion, interacting with others and social intercourse in general.
If you can't read properly because all thinking is done for you then how will you read an instruction booklet to operate machinery to using a microwave. Remember, a little knowledge is a dangerous thing. And that's why so many people believe "natural french" is safe or still indulge in unsafe sex.
Yes, technology when used well is good and doesn't dumb you down. The problem is when you allow it to use you. And therein lies the rub.