I agree with you, in order to fix a problem the article presents terms that are not suitable.

For instance in the context of a service like gmail, why we should talk about "cloud" or say "SaaS" when it is as simple as a "web application"?

PaaS IMHO it's better translated as "cloud applications platform", or "cloud application service".

Finally I don't think IaaS is acceptable as it covers too much things, especially two things that I would simply call:

* Virtual Machine Service (EC2, Linode, ...)

* Cloud Storage Service (S3, Dropbox, ...)

Edit: yes... I used three times Cloud in the end, so at least for me the problem is that "Cloud" alone means very little.