Well, even if one wanted to, a marketing exec really couldn't advertise Nintendo NES as a "general computer" since it had no keyboard nor ability to connect a disk drive and printer. The "toy" aspect was an intrinsic property of NES (the "E" in Nintendo _E_ntertainment System) rather than a marketing angle. Therefore, its focus on gaming dictated the type of commercials you could run to advertise it.[1]

From what I remember, the Nintendo NES was the first console where the quality of the games closely matched the real arcade versions.[2] Donkey Kong was a prime example. The NES version looked, sounded, and played like the real thing. (This wasn't true arcade games licensed & ported to Commodore 64, Intellivision, Atari, etc.)

The combination of low price point with higher quality games I think were the key factors for its success.

[1] https://www.youtube.com/watch?v=vDFvkWY6tJU

[2] https://www.google.com/search?q=donkey+kong+arcade+original&...