Why do old games use flashing as means of showing damage?
... Not all games did this, but it was very common, to the point in practically became a trope, and today many games that aim for the "pixelart" look also emulate this.
Games were of a limited resolution, it would be very difficult to show a little piece missing to indicate damage. There needed to ...
Just wanted to add my 2 cents.
Making the enemy blink upon damaging them was/is an effective way of informing the player that the enemy took damage.
I remember plenty of times seeing my weapon "strike" the enemy but the lack of blink let me know that my attack failed without needing to constantly check if the enemy's HP bar decreased.
Because it was an acceptable way to show damage
Remember who's playing these games. Primarily it was children. Games back then were entirely aimed at children (or at least young people). With that in mind, some way of showing damage without graphic imagery became necessary.
As a counter-example, consider Barbarian which had more graphic depictions of ...
In addition to the other answer and comments, a character would often enjoy a brief period of invulnerability after sustaining damage — this period was indicated with the character blinking. The blinking effect here helps suggest an ethereal state where you can’t suffer more physical damage.
So, why was this so widespread? Was it simply because it was easier to do than anything else (and, you know, limited hardware of the day),
Exactly that. To make a sprite blink, all you got to do is to set it to be not displayed and then displayed again. Usually just writing a single register or pointer or setting a flag to skip drawing it. Neither any ...