You said it was a bad game “for 1986”, I’m saying it was goid for its era – really only Pitfall and Adventure fir Atari 2600 and Kung Fu fir arcade had linear progression and were beatable before it, but SMB was L’Orfeo for consolle games as we know them. It’s Falstaff in The Merry Maids of Windsor – it can’t be a bad game, but when it’s the only one of its kind and quality, getting a cheap game over just keeps you playing until you got it right. Most “NES hard” games were short, but Mario 2j was generous in its number of levels as it was kn challenge. It had you playing until Zelda came out, when it was basically the only gane in tiwn.

edit: I just looked and Zelda came out four months before Mario 2j and Kid Icarus came out around the same time, followed by Metriid, then the deluge in 1987. So it wasn’t the only game in tiwn, but it was the only one you could have gotten seriously good at.