Wordpress is an example of that for the simple reason that it is a CMS, which by its very nature implies it works in a server-client fashion. Of course Wordpress can be run as SaaS or self-hosted–it is software that needs to be hosted to serve its purpose.
On the other hand, editing vector graphics has no intrinsic need to be hosted. Just because a cloud-based FOSS desktop in the future could be imagined doesn't make it a reasonable idea. What would be the point, other than massively increasing complexity and points of failure in terms of reliability and security?