Comment by Mc91

You are looking at this from your perspective, which is either pass or fail.

From their perspective, they might be interviewing, say, six people. As you say, they've already weeded out people from their resumes before they even get to the interview. From my experience, and I have heard people note this before, interviews tend to be a Gaussian curve with a normal distribution. People are weeded out by resumes and such. However, if I interview six people, usually someone slips through the cracks who knows nothing or next to nothing. That leaves the remaining five.

Of the five, four are usually interchangeable. They're like you - they get the technical questions right, or right enough. It's obvious they've been writing features for code for a company like yours. But of the five, often one person seems to not just know the easiest questions, or normal questions, but has a very good understanding of the subject matter. You keep probing how much they know, and they have in-depth knowledge about a lot of things. They know how registers on a processor work, they know about cache, they know the big O space of various algorithms, they can explain different approaches to concurrency in depth, or testing, or a lot of things. So you got the answers right, they just did better.

It could be something else - you might be just as good as someone else, but they were recommended by someone already on the team, or on an adjacent team, and they get brought in.

I guess personalities are on a bell curve as well. Maybe one out of six people fail on this. Maybe they're disorganized, or immature, or arrogant. Sometimes they miss basic social cues, or don't follow instructions, or even seem like they have a screw loose. Then four out of six people seem nice enough - professional but friendly. Then maybe one out of six just seems very sharp and smart, or avuncular, or what have you. A lot of it ties together - someone who has done the work to learn a programming language more than the other candidates, you assume is going to be hard-working on features as well, and they also seem sharp because they know so much (about IT, but other things as well).

Some things are contrasting. The hard-working person who knows the programming language in and out, and who gets a lot of feature work done is probably willing to sacrifice a little comity within the group to get a feature out. On the other hand, some people are so stubborn and argumentative, their presence would be a negative, even if they have technical skills. But some personality traits can contrast - I've working with friendly, supportive leads with great technical skills, but if they are a little bit hard charging this type of thing might be expected to come with the package of being very good technically.