The bottom line is: can you do the job?
Certificates and other continuing education type courses however, do indicate to an employer (and to your clients if you are self-employed) that you are keen to keep up with developments. What is learnt on the job does not necessarily mean that those skills are at the 'cutting edge' of your profession. In my opinion, certificates and other higher education degrees should build on your current 'hands on' knowledge and take you beyond what you already know.
Certificates might just confirm that you are keeping up to date with developments in your field. This is an important indicator of your commitment to your profession, but they do not encourage you to question issues in your field, and so they do not assist with expanding the boundaries of your expertise. Some graduate degrees might take you beyond the present and encourage you to explore beyond what is known to what could be.
Certainly, certificates and graduate degrees should not be accumulated for the sake of accumulation, as Razan Khatib indicated. That would be a waste of time and resources. Each must make a positive contribution to the professional's effectiveness.
I also agree with Booboo that the more dynamic companies care far more about existing skills and the ability to do the job, while the more traditional conservative businesses will put greater emphasis on paper qualifications. But the latter is only true when they are looking at employing a new graduate; as soon a they are considering an experienced applicant, then it comes down to evidence from previous positions which shows that the person has the capabilities to do the job well.
Further education has its place and its value is determined by the goals it is intended to achieve.
