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I've said this before but the game design basis shifted between the 2600 and the NES.
Atari 2600 (and arcade) games were usually centered around reflexive action. You could pick up the mechanics in minutes, for the most part, and difficulty was most often represented by increasing enemy speed and frequency. This ages very well. I can go play Defender right now and have a blast.
At the skate shop I used to work at, we had both an Atari 2600 and a SNES; the Atari was, without a doubt, the most popular for everyone to gather around and play in small chunks. There was no need for tutorials and, most importantly, little need for memorizing.
The memorization aspect is what really came into play with the NES and something that I never really loved. Games began to lean on the mechanic of "death by not knowing what comes next". The challenge became less about reacting than knowing when to act. This made small games feel bigger and became another aspect of increasing difficulty.
I could beat most of my NES games while barely paying attention. Once I learned the timing for each one, they generally became cake. I used to beat Punch-Out and Double Dragon II, for example, with the controller behind my back in order to make it a bit more challenging. With most of my favorite Atari 2600 games, I just played until I lost.
