Fundamental development in the disciplinary topics of mathematics, statistics, and linguistics was procured from a comparative ground-level hundreds of years ago as opposed to what we have unearthed today. The advantages and resources currently available to the vast public are, of course, the most they have ever been in history. This goes without saying. "Discovering" tactics to break codes and ciphers that were once considered the most advanced techniques by exceptional cryptanalysts is certainly not as easy a task without the long history of code breaking (in the colloquial meaning of the term) that had come before us.
The ability to learn methods such as frequency analysis from a quick Google search is much less arduous a task than inventing them without any previous notion of such a possibility. Even assuming that today's amateur cryptanalysts aren't explicitly searching "how to's" from public databases, the idea of frequency analysis and any analogous general form of use is very comfortable and familiar. Perhaps teachers from grade school distributed puzzles aimed to unscramble words and phrases or your classmate used a simple cipher as a way to ask out their prom date. Experiencing or seeing a number of similar events throughout our lives inevitably ingrains the technique somewhere in the back of our minds, at least implicitly.
Noting the above, it is truly incredible to acknowledge how commonplace once incredible and cutting-edge discoveries are considered in the present day. This will always be observed, even beyond subjects regarding cryptography, as a natural progression of time.