I believe the reason for the "Just be yourself" advice is to ask people to be calm and confident, and not to lie about experiences. In that context, it is good advice. But it would be a mistake to think that you don't need to be good at selling yourself. Being good at positioning yourself and experiences in a positive manner, have good communication skills etc are important to succeed at an interview. Perhaps "Be the best version of yourself" might be better advice.

I have cut interviews off at the 10 min mark where candidates try being themselves, and the 'themselves' are unhireable due to self-entitlement attitude. Key thing is to come across as hire-able. In your specific case of being introverted, it is ok. Don't be too harsh on yourself. As long as you dont come across as sucking energy but rather giving energy into the room, that should help the interview a lot. Work on giving energy, albeit selectively.

I think when it comes to “being yourself” for job interviews, something to consider is that if you aren’t honest about who you are and what you want, it might be difficult to find a company whose work culture suits you. I don’t think it’s worth it to try conforming to what you THINK might make you stand out. Even if you’re introverted, that shouldn’t be a barrier to getting a job. You can stand out by having interesting qualifications, by learning what questions to ask when the interview is over, by doing your research about the company and position you’re interviewing for. You could even find a way (if possible and applicable for the industries you’re applying to) to make your CV a little more unique. I understand being nervous about interviews. It is super daunting for a lot of people to have to know how to act in that situation where you may feel a lot of pressure, especially if it’s a job you really want. But being yourself is the best way of finding a job that will actually suit you in the long run. And finally, I find it so fascinating that you claim to be bad at “expressing yourself”. You made this post explaining how you feel and what you’re concerned about, and that has been conveyed very clearly. So maybe you aren’t as bad at self-expression as you think!

"Just be yourself" = BE AUTHENTIC.

“Just be yourself” is an over-rated advice. Just ignore this advice. The only advice you need is “go with flow” like in a driving test. You worry too much which leg to move forward, sure make mistake one and trip! During interviews I will dismiss someone not showing up for the interview thinking his 4 pointer will get him through. No effort to be PRESENT in the interview like it’s a nothing process. Yeah, go with flow and wing it with your honesty and show what needs to be shown - you and what you can do.

Interview is not I win when I secure a job. Interview is actually finding the best place that fits you. You choose your boss and your boss choose you. Both must be perfect match. By being yourself, you can find the boss or managers that are also introvert. No all managers are extroverts. If you fake it to be an extrovert, you will waste your time as you are the odd one out. Everyone will find out eventually who are you. Find a company that fills with introvert then you will feel in place. I still strongly believe in being yourself during interview is the best to find the job that fits you.