I agree with many of the comments here that this "problem" is not only related to the WordPress community. Titles are just that. Titles. Unless one got it from an academic degree (and even then), it only reflects how a person labels and markets itself in a business.

My favorite title is definitely expert, it sounds so professional but at the same time it is extremely vague, and I try to avoid it at all costs when writing about myself.

Instead of titles and certificates, people should focus on what clients or other people in the community say about a person they want to hire. Testimonials, references, LinkedIn acknowledgements and so on. A reputation certainly means more than a title or self-made profile. Last year I was part of a small developer team creating a new so-called social media platform (yes, another one). The difference in this one is that you don't create your own profile, but rather you let your friends and network do it.
It's www.praice.com if anyone wants to check it out, and while I no longer take an active part of the project, I definitely see its potential in e.g. cases like this.

Joachim
Engineering Engineer and MySpace Expert