You have to do this everywhere. There are limited resources. You are competing for them with others. You need to convince a gatekeeper that you deserve those resources. In academia, you are competing for grant money, lab space, etc. on the basis that your work is of more import than that of someone else. In enterprise software sales, you are attempting to convince a customer that your product is a better solution to their business problem than of some competitor's. In an interview, you need to demonstrate that you can accomplish a function better than one of your peers who is also vying for the job, and probably has an almost identical skills profile to you.
EXPLAINING something you've done.
In an actual interview, when they are talking about something they've done and explaining it, the interviewer will be able to ask more questions and hopefully (as an interviewer) have enough of a technical background to separate the BS from the skills.
If two chemists are talking to each other about chemistry, one's not going to be able to easily just make stuff up that the other blindly accepts.
* Talking about something you've done? You're selecting for marketing, not programming.
* Letters of recommendation? You're selecting for ability to network, not programming.
* Academic qualifications? You're selecting for persistence, not programming.
* Offline tests? OK right now because they're a minority, but I guarantee if they became the standard, you'd get an astounding amount of cheating.
I'm not a marketer and I really resent how in academia to have any chance you have to "sell sell sell". I appreciate anyone who gives me a chance to just objectively demonstrate my abilities, whether I do well or whether I do poorly.