PostgreSQL isn't enough scalable as Oracle or DB2

Hi, have a nice day. I'm reading about PostgreSQL Architecture Fundamentals
for taking the Associate Exam, and i found this article:

http://reshmaparveen.blogspot.com/2009/12/postgresql-system-architecture.html

I was reading the Scalability section, where it mentions this:

*Even though the query receiving thread is alone it still offers better or
equal scalability to MySQL. In terms of multi-computer scalability,
PostgreSQL does not scale at all. For large cluster based clustering,
commercial database systems are by far more mature; some good
implementations include Oracle and DB2.*

The article is from 2009 and i know that PostgreSQL has been getting better
and better but i don't know if this is true or if this have been surpassed
or if it was a lie.

Regards.

***************************
Oscar Calderon
Analista de Sistemas
Soluciones Aplicativas S.A. de C.V.
www.solucionesaplicativas.com
Cel. (503) 7741 7850 Tel. (503) 2522-2834