Platforms, yup, that’s the main reason. There are so many really advanced, and importantly free platforms to use for analysis. Software such as Metatrader was breaking open doors that weren’t available to the average trader, and still today allows people with ideas, to put them into practice.

The main point I think you missed is that it is easier for most people to understand a currency and what affects it. There are (apart from economic data) not that many ways it can be manipulated on a large scale.

Stocks however, you have to factor in the sentiment towards a sector, you have to have a grasp on a companies fundamentals, and even have a beady eye on economic data and overall market conditions. Too many variables for the average brain.