It doesn't really make sense to ask regarding these younger drivers. The same could have been said of Kimi, for example after 6 years in F1, but prior to heading off to Ferrari and then Lotus. Alguersauri and Buemi didn't have much of a chance to hop around before they lost their drives, but they may be back yet. Vettel may move on to another constructor down the line. Perez at Sauber and Maldonado at Williams were likely to have had some engineering consistency for their time in the sport so far - yet Hulkenberg has had a less stable team. So it is more a question of where you start and how long you stay before you move on.
Your little rant didn't answer anything.
If Vettel had been in F1 for 15 races sure, but he has had over 100 races now. Thats a F1 veteran really.
Also the question isnt "Can any member come in here and downplay the significance of a question in order to achieve his or her agenda"
That wasn't a rant, this is a rant.
Boubon said at the start of his post that it's hard to talk about drivers at the beginning of their careers, because if they stay in the sport they're apt to change teams a couple of times, and if they don't they weren't good enough to worry about how much of their time was spent in a given designers car. Then went on to talk about Kimi who did spend several years at McClaren when Newey was there, but then moved on to other teams. Granted he didn't supply a percentage for how much of his time in the sport was in a Newey car, but did address your question.
At no point was the "significance" of your question, such as as it is, downplayed, nor was there any agenda of his own being displayed other than giving an opinion which didn't support your agenda.
I think that you're upset that your petty little attempt to continue to downplay Vettels achievements might turn into an interesting conversation instead of a bunch of people coming into this thread agreeing with you about how crap Vettel would be if he wasn't driving a Newey designed car.