Regarding mnemonics not being as popular today, it’s necessary to understand what happened to them.
There’s a very good book that explains the history of memory and mnemonics. It’s called “The Art of Memory” by Frances Yates.
I discovered while reading the book that in the past, mnemonic techniques were the basis of learning in various cultures, especially in academia. Particularly the memory palace and the techniques from the book Ad-Herennium. For a long time, the Catholic Church used mnemonic images, which originated the images of saints in churches. It was a way of explaining who that saint was and what they did through a visual image. It was almost considered a sacred way of learning. Many said that by creating memory palaces, you were accessing a supernatural world, and they even created religions based on this, where memory was the foundation.
However, as far as I remember, a member of the Catholic Church who knew the technique wrote about the techniques WITHOUT INCLUDING the religious aspect. It was one of the first books on the subject that didn’t mention anything religious. This book was successful, along with others, and the Catholic Church began to prohibit the use of mnemonics, saying it was something profane.
Much later, Protestants in England also prohibited the use of mnemonics because, by creating images considered impure in the mind (sexual, for example) to remember things, we would be creating “idols.” And the goal was to eliminate idols both inside and outside the mind.
Along with this, a Protestant named Petrus Ramus developed Ramism, which is a way of learning WITHOUT USING MNEMONICS. This method was considered pure and was based on finding logic in things, creating a structure similar to a mind map, and then memorizing through repetition.
Ramism was the most widely used study method in England at the time, and later, when England colonized other countries, it passed the Ramism method on, until it reached the present day.
Here in Brazil, where I currently live, the Ramist method is used in the classroom (obviously it doesn’t have that name, but the structure is practically the same).
I’ve summarized it very simply, but this is the essence of how mnemonic devices went from being quite common to being demonized and almost extinct.
I recommend reading the book so you can better understand how this happened. In addition, the book covers many other things, such as Giordano Bruno and how mnemonic devices survived throughout the centuries.