Well, yes.
Magic did become weaker, but more than that, technology is the great equalizer. One hundred years ago, the average person could neither read nor write. Now we all have access to the sum total of human information in a few seconds.
Magic ceases to be magic once it's understood and mechanized- it then becomes a science. This is already happening with allomancy.
Why use a person when you can use a far stronger, usable by anyone, machine?