The Atari fuckups aren't as huge as you make them out to be, but if you believe in that bullshit then it would explain why you sound like you don't know what you're talking about.
The point I see here is you are shitting on them as being totally unable to take back the market they were still relevant in the mid-late 80s. More relevant than Sega, which was arguably getting it's ass kicked by the relaunched Atari 2600jr, in a hypothetical absence of the NES. You claim that computers would have taken off for gaming and parents would have went into debt for them against any rational convention, if knowing the way things were back then in general. It didn't happen, and it probably wouldn't have happened considering Atari's console was still around with games on shelves up until the 90s.
If they launched the 7800 as intended with the POKEY, they would have had arcade games in the home for 84/85 and the market would have rebounded from the crash by buying the next gen box with the better graphics/sound. The NES would have been in for a fight. If NES didn't show up and computers did take off and replace consoles, Atari was still the "gaming brand" 2nd option, competitive with the C64 in the computer market, before and after a totally different computer company took over their brand and products.
One way or the other, Atari would have been there. They mattered more than Sega in North America until the Genesis launched, even still up until late 90 when Sega found it's footing. Nintendo owned it all.