The real issue is careers valuing where papers are published over what they contribute, and incentives won’t change until hiring and funding reward depth over volume.
And who is the arbiter of that? This is an imperfect but easy shorthand. Like valuing grades and degrees instead of what people actually took away from school.
In an ideal world we would see all this intangible worth in people's contributions. But we don't have time for that.
So the PhD committee decides on exactly that measure whether there are enough published articles for a cumulative dissertation and if that's enough. What's exactly the alternative? Calling in fresh reviews to weigh the contributions?
We already know there is some way to do it because researchers do salami slicing where they take one paper and split it up into multiple papers to get more numbers, out of the same work. Therefore one might for example look at a paper and think, how many papers could one get out of this if they were to take part in salami slicing in order to get at-least some measure of this initially.
But for academic or other high-level research jobs, whoever is doing the valuing is going to look at a lot more than just the venue.
Depends on where. In some countries (e.g. mine, Spain), the notion that evaluation should be "objetive" leads to it degenerating into a pure bean-counting exercise: a first-quartile JCR indexed journal paper is worth 10 points, a top-tier (according to a specific ranking) conference paper is worth 8 points, etc. In some calls/contexts there is some leeway for evaluators to actually look at the content and e.g. subtract points for salami slicing or for publishing in journals that are known to be crap in spite of good quartile, but in others it's not even allowed to do that (you would face an appeal for not following the official scoring scale).
Remember that nobody is a passive actor in the system. Everyone sees the state of conferences and review randomness and the gaming of the system. Senior researchers are area chairs and program chairs. They are well aware and won't take paper counts as the only signal.
Again, papers are needed, but it's really not the only thing.