Is being Vulnerable really beneficial?

First of, it depends what you understand vulnerability to be.

To truly be able to open up and be vulnerable you need inner strength. Otherwise you're prone to taking things personally, have knee-jerk reactions etc. Then it's easy to say "Everyone is so mean!" or "being vulnerable isn't a good thing."
While the problem is that you haven't developed enough inner strength (yet).

Let's look at the opposite to get clear why being able to be vulnerable is so important, and beautiful: not being vulnerable is interacting with walls up.
You cannot express yourself properly when you have walls & shields around yourself. Nor can you be seen for the beautiful being you are as people will barge into the energetic walls.
Then you may not feel hurt so often because the walls take the brunt of things.
But do you truly feel good behind your walls?

When you have inner strength the need for walls vanishes. You won't get hurt much either as people see you differently now without those walls. They see the real you. And in case you do get hurt you have the ability to react entirely differently. Not by taking it personally, having knee-jerk reactions etc.
It'll feel like a mosquito prick, not like being bulldozed. Because you're now strong!
But you do need the inner strength.

As long as you don't have that you rely on the approval and acknowledgement of the external. That makes it almost impossible to be vulnerable. You then lean on the external too much while you should lean on your inner strength.
Ironically this makes you very vulnerable as you totally depend on what the external makes you feel, react to what they say and so on.
But this kind of vulnerability isn't the one that is meant when we say that being vulnerable is a good thing.

The one that is meant comes by itself when you have your inner strength. You can then open up, aren't nearly so afraid to get hurt anymore because you don't depend on the external moods and opinions. You have your own inner truth and strength to rely on now!
So you can open up, be vulnerable, which allows your intuition to work much better as well. Without the old walls & shield the antennae of your intuition can come out. They will help you as they'll let you know who, what, when is good for you and who/what/when isn't.
You are able to decide to leave or stay or take some other action, from strength. No longer hiding, fleeing, out of hurt or fear.

It truly is life-altering.
It takes personal growth & development. And time. But then it'll quickly come, bit by bit.
And you will notice it! Maybe not in all areas of life in one go, but that's okay.
Don't demand too much of yourself.
Baby steps are fine.