The PS3 early sales are what they are though too. That's not really an opinion.
Where is all this love/appreciation/benefit of the doubt there, if it supposed to exist it sure as heck didn't benefit the PS3, 3DS all that much.
4/6 of the systems people consider "most successful" come from a history of having a predecessor that wasn't well supported for even 5 full years (let alone 6/7/8).
1. PS2 - predecessor had long support
2. DS - predecessor had less than 5 years of good support
3. PS4 - predecessor had long support
4. Wii - predecessor had less than 5 years of good support
5. XBox 360 - predecessor had less than 5 years of good support
6. Switch - predecessor had less than 5 years of good support, will obviously rise up this list.
The only 2/6 examples that had long good support from their predecessors are Sony systems. Biggest failures Vita, Wii U had predecessors with fairly long cycle support, biggest mid-tier disappointments, 3DS and XBox One also had predecessors with long support cycles.
You can't really debate any of that stuff.
The last Nintendo hardware system that was a large success succeeding a prior system with a long product cycle is the Game Boy Advance which is now almost 20 years ago, so they've had serious issues following up on systems with long product cycles for several decades now.
Even Sony's long tail support is really because they have so much 3rd party support, it's not really Sony themselves doing much for these systems once the successor releases. There are a lot of people that just want to play like FIFA every year and don't necessarily want to buy a new console, Sony is the main benefactor of that.
Switch predecessor, 3DS have good lifetime support. Switch has TWO predecessors.
SNES - long predecessor support
GBA - long predecessor support, short lifespan, but great sales
3DS - long predecessor support, best selling 8 gen portable.
This predecessor, has good or bad support that has a minor impact on the next generation.