I don't consider those combos. And like you said, Ness may be able to hit people successively, but it doesn't constitute a combo unless it's inescapable.
Also, watch Simna's videos, use the weak bair to combo into finishers better. He used it in the combo video preview if I remember corectly.
The handicap of being comboed while not being able to combo is immense. If Ness gets hit once corretly by a good Falco, he's up 40-60% instantly, whereas it takes Ness an immense amount of effort to get enough hits into to create that percent. That is why Ness is bottom tier.
I'm still trying to figure out how to overcome that...edgeguarding is one way, but Ness doesn't have a great recovery either so its evened out. YYG and PKT mindgames are another way, if Ness can get in his big blows, it really evens up the damage, but they're incredibly difficult to pull off, especially against people that are good enough to really destroy Ness.
Honestly it's an irritating situation. Ness doesn't have the ability to do lots of damage quickly in any situation, he's the kind of character who builds it up over the course of a battle, but in order to win with that strategy, you need to be able to avoid the enemy a lot while hitting them, fairs and nairs, uairs, and PK Fire are pretty much what you're working with. Use the bat and your bair if you can, but in all of that, Ness has it harder than anyone else. The only other real way to fight against those odds is by killing people at low percentages, which Ness is...pretty bad at. Not horrible, but also not good.
I'm hoping Simna's combo video will reveal some newer strategies on taking people apart with Ness. Just small things, really.